a speech by Chris Corti

Abstract

Control of grain (crystal) size in jewellery manufacture is important for several reasons. It affects the properties of the alloys – mechanical, chemical and physical. These, in turn, influence the manufacturing process and the jewellery’s behaviour during wear by the customer.
There are a number of ways grain size (and shape) can be controlled in precious metal jewellery alloys – by casting, working and annealing and by use of alloying additives that refine the grain size during casting and during working and annealing. These are reviewed and discussed in terms of their mechanisms, ease of use and their effectiveness. Some of the problems that can arise from lack of control will also be discussed. The focus of the presentation will be on gold alloys but all precious metals are considered.

Introduction

Anyone involved in the making of jewellery should have an appreciation of the nature of the metals and alloys with which they work and understand how alloying and processing of the metals influences the microstructure and consequently their properties. For jewellery, we focus on the alloys of the precious metals – gold, silver, platinum and palladium, all four of which are inherently ductile metals – but what I say is of general validity and applies to most metals. 

Two fundamental points to understand are that¹:

• Alloy composition, microstructure and processing history are interrelated, Figure 1, and jointly influence an alloy’s properties, be they chemical (e.g. corrosion and tarnish resistance), physical (e.g. density, colour) or mechanical (e.g. strength, malleability, hardness). These, in turn, influence manufacturability and service performance.
• Most metals and alloys are composed of many crystals, or grains as we metallurgists call them; thus, most alloys are polycrystalline. There are some rare exceptions such as single crystal aero turbine blades and amorphous or glassy metals. 

In this presentation, I want to focus on alloy macro- and micro-structures, particularly grain size and shape. How we can influence them by casting, alloying and by mechanical working and annealing? Why are they important?

Importance of grain size to jewelry

As jewellers attending this Jewellery Technology Forum will know, metallurgists pay some attention to the crystal, or grain, size in their alloys. We talk about ‘large (or coarse) grains’ or small (or fine) grain sizes and generally state the desirability of the latter in terms of jewellery production. The terms ‘large’ and ‘small’ are, of course, relative. But for practical purposes, ‘Large’ will usually mean grains of the order of millimetres or larger and ‘small’ will refer to grain sizes of the order of tenths or hundredths of a millimetre (1 – 100 microns). You may also hear of grain sizes referred to in terms of an ASTM numerical value. This is a comparative method of measuring grain size. The higher the number, the smaller is the grain size.

Why is control of grain size (and shape) important? Well, it is down to the relation between the grains (crystals) and the grain boundaries – the region at the junction of adjacent grains – and their relative influence on mechanical deformation processes. Grain boundaries are where the atoms sitting on the crystal lattices of adjacent grains do not match across together, creating a narrow region of imperfect crystal, Figure 2. Often, these can be a preferred site for deleterious impurities and second phases, leading to embrittlement. At low or ambient temperatures, the deformation process under an imposed load is governed mainly by the dislocation slip mechanism within each grain (dislocations are linear crystal defects responsible for deformation on crystal slip planes). Without going into deep explanations, the outcome is that alloys with finer grains are stronger than those with large grains, and this effect is expressed by the Hall-Petch relationship in which yield strength, σ_y.s., is inversely related to the grain size squared:

σ_y.s. = m/d² 

where d is the average grain  diameter and m is a constant. The yield strength of a material (known also as the Elastic Limit or  proof stress) is the stress required to start plastic deformation and is smaller than the ultimate tensile strength (‘UTS’).

Thus, the jewellery is stronger and harder if it is fine-grained and, beneficially, it is also more ductile and less prone to cracking, impurity embrittlement and the ‘orange peel’ surface after deformation. As jewellery is generally only subject to relatively simple stresses (loads) at ambient temperatures, whether in a production environment or in service, a fine grain size is therefore desirable. This is generally true for other non-precious engineering components such as sheet steel for car bodies and white goods.

On the other hand, engineering components can be subjected to often-complex stresses over long periods at high temperatures; for example, turbine blades and disks in jet engines and boiler tubes in utility power stations.  At these high temperatures, the main deformation mechanisms are phenomena such as creep and fatigue. Creep is the slow deformation under a steady low stress or load and fatigue is the mechanical failure under an alternating load. The lead sealing on a tiled church roof is actually at a hot working temperature and so slowly creeps under its own weight.  Under such conditions, the grain boundaries are weaker and grains can slide over each other; hence, a large grain size is preferred as there is relatively less grain boundary area. In the ultimate, such as gas turbine blades, we prefer to eliminate grain boundaries, so we find use of directionally solidified alloys and even single crystal alloys for optimum creep and fatigue strength. An extreme of fine grain sizes is a phenomenon known as superplastic deformation, whereby alloys with stable, fine grain sizes can be gently deformed at temperature under low stresses to very large deformations, just like Swiss cheese fondue.  Several titanium aircraft components of complex shape are manufactured by this technique including the very large fan blades on Rolls Royce jet engines. Interestingly, fine-grained sterling silver can be superplastically deformed under the right conditions² and I would expect some other precious metal alloys also to do likewise. But to date, that ability has not been developed or commercially exploited in our industry.

Examination of microstructure: metallography

As many of you will also know, we can examine the microstructure and measure the grain size of a piece of jewellery metal; due to the scale of this, it is often performed under an optical microscope. The process of examining grain size and general microstructure is called ‘metallography’. Figure 3 shows the microstructure of both as-cast and cold worked and recrystallized gold alloys. There are obvious differences in appearance and these will be explained later.

Normally, if we wish to examine the macrostructure or microstructures of an alloy, we need a flat polished surface as optical microscopes have a limited depth of focus. In order to expose the features such as grain boundaries and second phases, we often need to etch the surface with a corrosive liquid such as acid. As grain boundaries are less perfect than the crystals, they etch preferentially to reveal themselves. As different crystals are oriented in different directions relative to the plane of the surface, they also etch at different rates and so appear of different contrast or colour to the eye. Where more than one phase is present, these also etch differently and usually show themselves as different colours or shades of darkness.

If we need greater magnification than we can get in an optical microscope to see the features of interest or we have an uneven surface such as a fracture, then we use a scanning electron microscope. Here flatness of the surface is not such an issue as in optical light microscopy and we can often see different phases by atomic number contrast, without the need for etching (see figure 22 in reference 3, for example)^3,4. The heavier elements appear whiter under the SEM and the lighter ones darker, so giving rise to differences in contrast with varying alloy phase composition.

Casting

Melting and casting is a process for producing alloys of the desired composition and also for specific shapes. These can be either net shapes, as in investment (lost wax) casting, or stock materials, i.e. ingots, that can be further processed to modify the shape, structure and properties. Casting involves melting and the solidification of molten metal. Subsequent mechanical processing of ingot materials enables us to break down coarse, non-uniform structures to more desirable refined structures better suited to the purposes that we require in manufacture and in subsequent service and generally have improved, more consistent properties.

The structure of cast alloys depends on the rate at which we cool and solidify the metal which, in turn, depends on the size of the casting and the thermal conductivity of the mould material. Thus, the structure of large ingots will differ from that of small investment castings. We will explore the influence of casting conditions shortly.

Influence of solidification on grain size and shape

As has been mentioned before^5,6, pure metals solidify at a fixed temperature; for example gold solidifies at 1064°C and silver at 962°C. Most alloys*, on the other hand, solidify over a temperature range: the liquidus temperature is the temperature above which the alloy is completely molten and is the temperature at which solidification starts on cooling; the solidus is the temperature at which solidification is completed and thus below this temperature the alloy is completely solid. Between the liquidus and solidus, alloys comprise some liquid and some solid, often known as the ‘mushy’ or pasty state. The characteristics of solidification and the resulting structure are influenced by the temperature gap between the liquidus and solidus and the overall phase diagram for the alloy system.

[*There are a few exceptions, such as eutectic alloys which also solidify at a fixed temperature like the pure metals]

To understand the process of solidification, it helps to understand the atomic structure of liquids and how atoms coalesce to form solid material. The liquid state comprises mobile atoms in a dynamic, unstructured state. Some atoms will come together briefly to form a small cluster but these quickly break up.

As we cool a liquid (molten metal in our case), small clusters of atoms come together and stay together to form a nucleus. The formation of nuclei tends to occur at preferred sites such as a mould wall or at impurity particles/inclusions but can occur   randomly in the melt.  As the temperature falls, more atoms join the small stable clusters of atoms that comprise the nuclei in a structured way that is the crystal lattice of that metal or alloy. For our precious metals, that will be in the face-centred cubic arrangement discussed in another presentation¹. These are the embryonic crystals  (crystallites) that will make up our alloy. A fast cooling rate during solidification will lead to more nuclei forming and consequently, because each nuclei develops into a crystal or grain, a fine grain size results. A slow cooling rate leads to less nuclei forming and a resultant larger grain size. We should note that nucleation at inclusion particles is how insoluble grain refiners like iridium and ruthenium work in gold alloys, for example, by promoting nucleation.

These nuclei grow by adding more atoms from the liquid. They do so in preferred crystal directions, extending from the cube faces and branching out as the crystal grows. This results in a tree-like structure that we call a dendrite. All the nuclei grow into dendrites, each of which will have an orientation dependent on the orientation of the original nucleus. Each dendrite continues to grow until it collides with an adjacent dendrite. The interface between them forms a boundary. This we call the crystal boundary, or more usually, a grain boundary. Here, the atoms on each lattice do not fit together cleanly, so creating a thin region of imperfect crystal, as we have discussed earlier. Figure 4 shows some dendrites in a platinum alloy⁷. We can clearly see several dendrites, each pointing in different directions. We often see such dendrites in shrinkage cavities in investment casting. Provided there is feeding of more liquid metal, the spaces between dendrites eventually fill up to give solid metal. If there is restricted feed, then shrinkage cavities (porosity) will result.

If we examine an etched metallographic section of a cast metal under the microscope, such as shown in Figure 3, we can clearly see the dendritic structure. We also note that the dendrite centre etches up differently to the outer zone; this is due to chemical segregation, whereby the metal that solidifies first has a different chemical composition from that which solidifies last. This is known as ‘coring’. Why that is so, we can readily explain from the phase diagram⁶.

When we pour molten metal into a mould, it begins to solidify inwards from the mould walls as this is the coldest temperature. If a cold metal (e.g. iron) mould is used, as is usual for ingot casting, the rate of heat removal is rapid. Initially, a thin layer of fine grains is formed – the chill layer –  because of the high rate of nucleation. Then long finger-like grains – called columnar grains – begin to grow inwards from the chill layer towards the centre of the ingot, Figure 5.

If the metal casting temperature is relatively high, this columnar growth will extend into the centre of the ingot, Figure 6. This is not a good structure if you are going to roll the ingot to plate or sheet, as it may split down the middle (known as alligatoring, Figure 7), as this is also where impurities will tend to concentrate as it is the last metal to solidify.

When a ceramic (plaster) muold is used, as in investment (lost wax) casting, the cooling rate is markedly slower and equiaxed grains are formed throughout the casting. This is a preferred microstructure. Temperature of melt and mould can play a role in determining the as-cast grain size. The higher the temperature, the coarser the grain size.

Refining cast microstructures by working to improve grain size

As we have seen, cast microstructures may not be optimum for manufacturing or service. Chemical segregation (‘coring’) and coarse structures can lead to poor mechanical and corrosion properties. So working of ingot material serves two purposes: (a) to change the physical shape to that desired (sheet, wire, etc) and (b) to refine the structure. This may involve breaking down coarse grain structures, reducing segregation and refining coarse second phases to smaller, more uniformly distributed ones.

Much of this is best achieved by hot working the material, by hot forging or rolling, extrusion and/or drawing or combinations of methods. This will refine the structure but leave it more or less in a soft annealed condition. In hot working, as the metal deforms, it is at a high enough temperature for it to recrystallize (anneal) during the deformation.

If we wish to impart additional hardness and improved strength as well as a more accurate shape and superior surface, then we cold work the material, usually at ambient temperature. Here the temperature is insufficient to promote annealing.

If we overwork a material, it can crack or fracture, so we need to anneal the hard worked material from time to time to restore the soft, ductile condition and enable further working. Annealing involves a process of recrystallization, where the hard deformed grains reform themselves into new undeformed grains by a nucleation and growth process analogous to solidification.

Cold working and annealing: influence on microstructure & grain size

Cold working of metals results in an overall shape change. This is reflected by a change in the microstructure, where the grains must deform to accommodate the change in shape. This is shown schematically in Figure 9 for reduction by rolling. To achieve this, planes of atoms in each grain (crystal) must slide over each other, Figure 10, via crystal defects called dislocations. Such sliding occurs over several crystal planes in a complex way.

We also see this deformation in the overall macrostructure: Figure 11 shows one-half of the cross-section of a washer in the process of being upset into a wedding band; the heterogeneity of deformation is evident in its fibrous appearance. Most cold-working processes result in uneven deformation through the cross-section. In rolling or extrusion, for example, most deformation occurs at the surface, especially if only small reductions per pass are imposed. Uneven deformation can give rise to initiation of cracking from the surface, as Battaini has explained⁸. Such non-uniform deformation can also have repercussions on the grain structure on subsequent annealing when the process of recrystallization takes place. Recrystallization results in new undeformed grains replacing the old deformed grains.  The fibrous cold-worked structure is replaced by recrystallized new grains, as can be seen in Figure 12.

The resulting grain size after annealing depends on the amount of cold work, the annealing temperature and time. The more cold work, the finer is the recrystallised grain size. Annealing of material only cold-worked a small amount can result in large grains, which is undesirable (there is a critical minimum amount of cold-work necessary to initiate recrystallization, typically about 12-15% reduction). That is why annealing is often recommended only after substantial cold work, e.g. 60% reduction in thickness. The annealing temperature and time also play a part. Figure 13 shows a matrix of temperature and time of annealing for a 2N pale yellow 18 carat gold (cold-worked 70% reduction by rolling) and their effect on resulting annealed grain size (9). The variation in annealed grain size due to uneven amounts of deformation can be seen in Figure 14 which shows part of a cross-section of a ‘C’ shaped wire in an annealed 18 carat nickel white gold. The inside of the flange has a finer grain size and the outer regions have a coarser size, reflecting the uneven amount of deformation during rolling⁸. This may not be important in some instances, but it can be in others. Orange peel surfaces and cracking may result on further working, for example, where large grains are at the surface regions, as discussed earlier.

Figure 15 shows schematically the effect of annealing temperature on hardness/strength , ductility and recrystallised grain size. An important point to note is that if the annealing temperature is too high, then grain growth can occur and very large grains can result. This is undesirable and can lead to the ‘orange peel’ rumpled surface and cracking on further working, as noted earlier. This can be a problem for craftsmen during gas torch annealing as there is less control of temperature during annealing and a tendency to overheat the piece.  14 carat coloured golds are especially prone to excessive grain growth during annealing, as Grimwade has noted¹⁰.

Two-phase alloys: Where an alloy consists of two (or more) phases, there is an effect on grain size after working and annealing. Working the alloy leads to a higher level of dislocations (crystal defects) in the matrix phase due to the presence of a hard second phase and this leads, in turn to a finer grain size after recrystallisation during annealing. Sterling silver is an example of a two-phase alloy. 

Where the second phase is very fine, i.e. very small in diameter, and evenly distributed within the matrix phase, such as in age hardened alloys or micro-alloys, the second phase may inhibit recrystallisation  as the fine particles of second phase can pin grain boundaries and so higher annealing temperatures may be necessary. In such alloys, a larger or more uneven grain size may result.

Alloying additions to refine grain size: grain refiners

Very small additions of grain refiners, typically at levels of about 0.1% or less, are often added to carat golds as fine powders to promote a fine grain size in the alloy. They include iridium, ruthenium and cobalt. Iridium and ruthenium are effective in casting, where they promote nucleation of crystals during solidification, and cobalt is effective during annealing of cold worked materials, where it promotes nucleation of grains during recrystallization. Iridium and ruthenium are insoluble in molten carat golds, so act as nucleation sites. Figure 16 shows the fine grain structure of an annealed 18 carat gold with iridium additions, compared to that without iridium. If too much is added or it is not well dispersed, one can get nests of hard particles at the surface that give rise to ‘comet tailing’ defects on polishing¹¹. Note that grain refiners are not effective in silicon-containing carat gold alloys.

The amount of cobalt that can be added is also sensitive to copper content of the alloy, as Ott has shown12. Its effect in grain refining a 14K gold is shown in Figure 17.

Other metals have also been shown to act as a grain refiner in gold alloys, such as boron, beryllium, yttrium and the rare earth metals, rhenium, rhodium, nickel, barium and zirconium13-16. In a more recent patent, a combination of iridium, rhodium and ruthenium added as a copper-master alloy is claimed to be effective17.

Conclusion

In this presentation, it is concluded that, for jewellery manufacture, it is desirable to have a fine (small) grain size. It optimises strength and ductility and other properties such as corrosion resistance. Coarse grain sizes lead to ‘orange peel’ surfaces on subsequent deformation and enhance the tendency to crack as well as reducing strength, hardness and ductility. The yield strength is inversely proportional to the square of the grain size.

The influence of casting conditions on as-cast grain size and shape has been discussed in terms of nucleation of crystallites in the melt and solidification patterns. Melt temperature and mould material play an important role.

The influence of cold working on the as-cast macrostructure and the recrystallisation process during annealing has also been examined in terms of the resulting recrystallised grain size. Annealing temperature is an important factor to obtain a fine grain size. Too high a temperature can result in excessive grain growth, which is undesirable.

The use of grain refiners, such as iridium and cobalt  in carat golds, to obtain a finer grain size has also been demonstrated. The mechanism is enhanced nucleation of crystallites during solidification or  recrystallisation.

Acknowledgements

I would like to thank the organisers of the Jewellery Technology forum for inviting me to present once again and for their kind hospitality. I also thank many friends in the industry for allowing use of their figures and data. Many are courtesy of Mark Grimwade.

References

1. Christopher W. Corti, “Basic Metallurgy of the Precious Metals – Part 1”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 2017, ed Eddie Bell et al (Albuquerque: Met-Chem Research, 2017: 25-61. Also 2007: 77-108
2. R.W.E. Rushforth, unpublished work, Johnson Matthey plc, 1978
3. Stewart Grice, “Know your defects: The Benefits of understanding Jewelry Manufacturing Problems”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 2007, ed Eddie Bell (Albuquerque: Met-Chem Research, 2007: 173-212
4. Greg Normandeau, “Applications of the Scanning Electron Microscope for Jewelry Manufacturing”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 2004, ed Eddie Bell (Albuquerque: Met-Chem Research, 2004: 345-388
5. Mark Grimwade, “The Nature of Metals and Alloys” in The Santa Fe Symposium on Jewelry Manufacturing Technology 2001, ed Eddie Bell (Albuquerque: Met-Chem Research, 2001), 151-179.
6. Mark Grimwade, “A Plaim Man’s Guide to Alloy Phase Diagrams: Their Use in Jewellery Manufacture – Part 1”, Gold Technology no 29, Summer 2000, 2-15. The author (Corti) can supply a pdf file of this on request
7. John McCloskey, “Microsegregation in Pt-Co and Pt-Ru Jewelry alloys”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 2006, ed Eddie Bell (Albuquerque: Met-Chem Research, 2006: 363-376
8. Paulo Battaini, “Metallography in Jewlry Fabrication: How to avoid problems and improve Quality”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 2007, ed Eddie Bell (Albuquerque: Met-Chem Research, 2007: 31-66
9. Christian P.Susz, “Recrystallization in 18 carat gold alloys”, Aurum no 2, 1980, 11-14 The author (Corti) can supply a pdf file of this on request
10. Mark Grimwade, Introduction to Precious Metals, Brynmorgan press, Maine, USA, 2009; ISBN978-1-929565-30-6
11. Valerio Faccenda and Michele Condó, “Is ‘Pure’ Gold really Pure?”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 2004, ed Eddie Bell (Albuquerque: Met-Chem Research, 2004), 135-150
12. Dieter Ott, “Influence of Small Additions and Impurities on Gold and Jewelry Gold alloys”, in The Santa Fe Symposium on Jewelry Manufacturing Technology 1997, ed Dave Schneller (Albuquerque: Met-Chem Research, 1997), 173-196; Also: ibid, Gold Technology, No 22, 1997, p31-38 and “Optimising Gold Alloys for the Manufacturing Process”, Gold Technology, No 34, 2002, 37-44
13. W S Rapson & T Groenewald, Gold Usage, Academic Press, London, 1978. ISBN 0-12-581250-7
14. W Truthe, US Patent 2,143,217, January 1939 (assigned to Degussa)
15. P Johns, UK Patent 2434376A, July 2007
16. C Raub & D Ott, German patent DE2803949A1, August 1979
17. M Poliero & A Basso, US Patent 2015/03544029A1, December 2015

a speech by Beatriz Biagi

Jewellery trends evolve slowly. While other industrial sectors develop and adopt technological innovations quickly, the fine jewellery sector around the globe largely sticks to “same old” production and commercial procedures, feeling no urge to change. Cultural and security issues play a major role in both, keeping fine jewellery a priority for established customers and failing to address a growing number of potential customers.

Over the past 3 decades customer attitudes towards precious jewellery have not changed significantly for a large majority of rooted customers, for whom jewellery purchasing follows the cultural affinity matured over centuries and is essentially linked to special occasions, investment and heritage. This will most probably remain unvaried in the future, as long as the precious materials used are considered highly valuable. And as long as this customer segment remains big enough to justify keeping business practices unvaried. However, there are enough trend indicators showing that expectations are different for a growing number of clients and that what jewellery and luxury products represent will change over the next decades.

During the last 15 years it has become evident that the two major factors inducing a shift in our lives are Technology and Sustainability. We have observed new areas of opportunity being addressed often by newcomers and start-ups also in the fine jewellery scenario.  Precious wearable technologies, medical and communication devices, digital marketplaces and on-demand productions have steadily grown, bringing innovation into the international jewellery scenario.

As predicted in 2006, Sustainability has permeated across all products and is becoming a mainstream trend, as environmental and ethical awareness persistently grows. Although ethical correctness rises operation costs, there is ground to believe that customers will be willing to pay a premium for transparency and sustainability in jewellery or rather spend their disposable income in products and services of brands that adopt and can guarantee best practices. Putting sustainability as a priority by clients is a still quite irrelevant purchasing attitude in the jewellery business, but will gain importance in the years to come.

It is clear that in a luxury business based on gems and metals, environmental sustainability and ethical issues are not necessarily embedded in the system. Nevertheless, many companies are embracing the urge to protect the sources of the materials used, specially when talking about gems produced by living organisms, and to protect all persons involved in the process of extracting materials and transforming them at all stages, up to the production of fine jewellery or other luxury products.

For sure the jewellery sector is starting to adapt to today’s reality. In the past years we have seen a rise in online purchasing, as well as digital communication and client engagement.

We are seeing more significant efforts of businesses and brands to implement ethically correct procedures throughout the trade, aligning to voluntary standards and certifications.

On the other hand, experiential purchasing is gaining importance among young generations against purchases driven by investment or by attachment to traditions. These changes of attitudes and expectations towards fine jewellery in young generations will affect our sector differently, depending on the cultural environment of customers and their degree of affinity and attachment towards precious jewellery.

Today more than ever products and brands are successful if their stories are opportunely conveyed. In the past fine jewellery didn’t need to be supported by any communication or promotional activities. It literally sold just because it existed, as a large part of the population was culturally attached to what fine jewellery and precious metals meant. This is still the case for a large number of customers, especially in rural areas in Asia and among mature generations.

But as customers adopt a more metropolitan and global lifestyle, they lose the emotional connection towards fine jewellery. As customers become younger and more digitalised, they tend not to follow customs and habits dictated by traditional rituals as their parents and grandparents did. They start investing their time and resources in emotional products and experiences that satisfy their personal and needs and individual desires.

We are not talking about an ephemeral style trend. Any jewellery company that wants to be successful in the next decades needs to approach innovation by implementing a coordinated project that addresses design, product development and marketing. It is time to fully understand that it is not by using ideas of internship design students or by launching an Instagram influencer campaign, that we will build competitivity in the mid-term.

The development of successful proposals requires in the first place a correct problem setting and I would like to focus on that today. There are some fundamental questions to be answered regarding why somebody would want to buy our products and how. We have to understand the decision process involved in any successful product purchase and define the spectrum of possible paths to ideally pursue the best match between what we can offer and what our clients require.

Who decides for the style of the jewellery piece and who for the budget to be spent or invested? Very often these decisions are made by two (or more) persons independently, who nevertheless have to be sure they make the right choice even not directly confronting themselves with what the other person decides, but relying on the jeweller’s recommendations.

For which occasion will my product be purchased? A different story will be told if the jewellery piece is proposed for an anniversary, an engagement or a wedding, for a religious festival or festivity, for Valentine’s day or Mother’s day, as a treat or just for fun.

Who will purchase the product, where and how? A complete different set of values and buying attitudes need to be taken in consideration if the proposed jewellery will be self-purchased or bought as a gift, and if it will be bought by a woman or a man. This is the case also while analysing the purchasing process when bridal jewellery is at stake. For example, we can observe a complete different scenario selling a wedding set in India, rather than an engagement ring in the US. Furthermore, we need to understand the attitudes and expectations of those who will wear the jewellery pieces, their lifestyles, concerns and interests. And last but not least, we need to learn to communicate and engage with our clients addressing barriers we are already facing now, such as misinformation, false and counterfeited products or lack of trust.

But most importantly, we need to understand and attract our potential clients. Potential clients are by definition non-existing clients and actually we need to get to know them as accurate as possible, even before we start communicating with them. This segment represents the most difficult target, needing more resources invested for often uncertain returns. Our potential clients nowadays are represented mainly by young millennials and the youngest incoming gen-Z customers in metropolitan areas. Many consumer surveys show these young potential customers have different purchasing behaviours as precedent generations, due to the fact that they rely on digital technologies for every aspect of their lives.

This means for example, they will seek information and feedback from other customers on the net, rather than going to physical stores or ask advise form their families or close friends. Relying on digital technologies also means they demand immediate and personalised proposals, easy purchasing and hassle-free returns and product changes. They need to feel good about their choices, even if decisions might seem casual or thoughtless. It means they no longer keep long-term fidelity towards brands and can spontaneously change their minds. 

Digital technologies are in fact provoking a process of dematerialisation in every aspect of our lives. The meaning of wealth and luxury will inevitably continue to evolve, provoking a shift in the value perception of precious materials. Sustainability and ethical issues are being placed by the general public into the top of the value scale, which leads to questioning the need of using precious metals and natural gems in the first place. The idea of luxury itself is changing, in a world in which basic elements such as clean water, time and peace are to become the most-sought treasures. It becomes clear that in a longer term, the value perception of precious jewellery will no longer be as we know it today and that we need to start taking action to be able to satisfy our future clients.

Each company needs to understand which functions and services will be sought for by their potential client segment, which materials and products and will be accepted and which procedures must be put in place to be coherent. It is crucial to fully understand which message needs to be conveyed  today and what kind of stories brands and products will have to tell in the future, in order to change, not losing any of the existing strengths but rather strengthening the growing potential.

In any case the jewellery sector needs to seriously invest resources not only thinking which products will sell, but also which services and emotions should be accordingly offered. There are many positive attitudes linked to jewellery purchasing, that should no longer be taken for granted, but consciously processed to be built upon.

We should ask ourselves as jewellery makers and sellers which positive experiences do we evoke and can we provoke? To whom? We should understand what it means that our jewellery will represent a valuable treasure for a bride or will become a style statement for the wearer. What it takes to be seen and chosen with the help of a family jeweller or proposed by a recognised brand. How precious materials can become luxury accessories, personal communication or medical devices, religious or status symbols and how these bring security and happiness.

The role of precious jewellery is deeply embedded in human nature, and it will continue to be so, as long as it evolves into the shapes, symbols and functions clients look for. 

The positive elements that precious jewellery is capable of arousing in the pubic represent the most convincing source for competitivity and as such, need to  be wisely addressed and communicated. These represent the solid foundations that will guide us throughout the next decade to generate a compelling business personality.

a speech by Stefania Trenti

The Italian jewellery sector in 2019

Positive turnover and production also in 2019

• According to ISTAT data, production in the jewellery and bijoux sector recorded yet another considerable increase in the first 10 months of 2019: +19.5%, for the third year running. 
• Turnover also increased considerably: +11.4% between January and October 2019. Turnover increased for the tenth year running.

Price of gold is increasing…

As of the month of May, considerable global economic uncertainty led to a significant increase in the price of gold which quickly exceeded 1,500 dollars an ounce between August and September. It then continued to stand at higher levels than the mean value in 2018.
On average in 2019, the price of gold increased by 15.9% in Euros and 9.7% in dollars. 

…with negative effects on global demand

Global demand for gold jewellery reacted rapidly to the new price scenario, recording a significant drop in the third quarter (-15.6%), particularly in two main markets (China and India) and in the Middle East.

Source: Intesa Sanpaolo on World Gold Council data – Gold Demand Trends

Excellent performances for Italian exports…

In the first nine months of 2019, gold jewellery exports grew by 12.1% in quantity and by 8.8% in value in Euros.

…with widespread positive results on (almost) all markets…

…and districts

Provincial export figures are only available on a more aggregate level (including costume jewellery) and only in value (not in quantity).
All the districts registered positive development, with the best results in Arezzo. 

The success of luxury towed by Switzerland, France and Italy

Excellent results in the USA

The prospects for the next few months

Global trade picking up but trends showing modest growth

Forecasts for 2021

• Slight recovery in the first six months of 2020 but annual figure lower than 2019 due to a disadvantageous towing effect.
• A slight acceleration (of annual data) expected in 2021, also due to trade agreements.

From Asia, the first signs of cycle stabilization

USA cycle: controlled slowdown 

Consumers are optimistic

The employment market is the power towed by consumption: unemployment at its minimum since 1969

Family budgets are in order at last

Euro area: internal demand sustained by real incomes and tax policies

Foreign demand more favourable in 2020

Italy: still modest growth

• In 2020, we expect a slight acceleration to 0.3% (0.4% incorrect for working days) from 0.2% in 2019.
• A growth of 0.5% expected in 2021.

Budget law: resources destined for VAT blockage

The latest modifications have seen an easing and deferral of the plastic tax until July, a postponement of the sugar tax until October and a substantial zeroing of the squeeze on company cars. The manoeuvre has risen to 32 billion.

Note: effect on net debt in billions
Source: Intesa Sanpaolo processing on DPB 2020

Steady consumption thanks to good ready income dynamics

Growth can begin again in the medium term

Note: cumulated effects on the GDP of a 100 base-point drop in returns on Government bonds in the medium to long term (more or less in line with that registered in the last 6 months) (% deviation from the baseline) and on PA expenditure due to interests (in % of GDP).

Source: Banca d’Italia, MEF, Intesa Sanpaolo processing

Precious material prices  

Geopolitical uncertainty should continue in 2020 to support the price of gold which, in our expectations, should continue on a consolidation course, remaining within the mean in 2020 at around 1,500$/troy ounce, with a potential risk of increase deriving from ample liquidity on the markets and expansive monetary policies in all areas.

Euro in slight improvement against the USD within a 12-month horizon

Important Information

The economists drafting this report state that the opinions, forecasts, and estimates contained herein are the result of independent and subjective evaluation of the data and information obtained and no part of their compensation has been, is, or will be directly or indirectly linked to the views expressed.

This report has been produced by Intesa Sanpaolo S.p.A. The information contained herein has been obtained from sources that Intesa Sanpaolo S.p.A. believes to be reliable, but it is not necessarily complete and its accuracy can in no way be guaranteed. This report has been prepared solely for information and illustrative purposes and is not intended in any way as an offer to enter into a contract or solicit the purchase or sale of any financial product. This report may only be reproduced in whole or in part citing the name Intesa Sanpaolo S.p.A.

This report is not meant as a substitute for the personal judgment of the parties to whom it is addressed. Intesa Sanpaolo S.p.A., its subsidiaries, and/or any other party affiliated with it may act upon or make use of any of the foregoing material and/or any of the information upon which it is based prior to its publication and release to its customers.

a speech by Giulio Bevilacqua

Fashion and the electroplating business. Two apparently distant worlds linked by a technical dialogue that aims at getting things done: fashion brands on the one hand, and finishing “suppliers” on the other. The challenge: to build a business meeting point between strategic sectors that are tendentially little inclined to cross-contaminate and communicate in order to create a new way of thinking about luxury finishings.

A dialogue which inquisitive observation, together with 50 years’ experience, has led to three main aspects.

Aesthetics and fashion, or rather, linking electroplating finishing to the aesthetic value of the finished product. In the past, fashion, leather and footwear accessories were merely thought of as functional elements. Now, also due to the technical finishing skills, they are necessary and indispensable components, often even a distinctive element.

But how is it done? By studying the balance between shape, volume and finishing; by constant dialogue with the clientele; by analysing the input of the people employed in production and all by really listening closely to the surrounding world.

Research and innovation which means putting the experience gained and consolidated in the jewellery world with the biggest luxury brands at the disposal of the fashion supply chain. This translates into a constant experimentation of new processing techniques and research into global trends. One cannot stop at producing finishings with maniacal skill; the commitment, in any sector, is to be one step ahead in order to be able to offer the customers unique and distinctive fashion solutions.

Galvanic plating and sustainability… not a contradiction in terms but a feasible alliance. In times gone by, deciding the company’s environmental sustainability would not have been an option. On the contrary, the fact that it should develop and grow hand in hand with the company has turned out to be a natural choice, certainly not one dictated by legal obligations that did not exist at that time. Changing the idea, not only in the facts, but also in the collective imagination, that an electroplating company could be a sustainable company was a challenge that has become a concrete fact. Over the years, processing techniques, attention to the environmental context in the broad sense, as well as the more fragile contexts of the surrounding territory, have led to certifications, awards and recognitions that certify a virtuous “best practice” route at an organizational, managerial and production level in terms of sustainability.

These are the three pieces of a complex and articulate puzzle in which the various souls of savoir faire converge. A know-how that passionately moves towards creating and offering the fashion supply chain a replicable, recognized and recognizable product in processing, design, relations and service terms.

a speech by Vera Benincasa

Simulating processes has been mandatory in many companies from the most diverse manufacturing sectors for years. One only need think of the aviation industry where companies must be absolutely certain that the components produced have no micro-structural defects whatsoever and where a rejected part cannot be re-processed. 
Casting process simulation identifies areas subject to defects and helps to design the casting system in the most efficient manner. It also allows the causes of any inefficiency to be analysed and to understand how to increase productivity.
This system has been used for over twenty years in smelting processes in the automotive and aerospace industries and for some years now, it has also been adopted by our sector. 
In the jewellery world, lost wax micro-casting has always been linked to operator experience or trial and error. Nowadays, simulation software can optimize the entire process starting from the very first prototype design to the mass production of jewellery items. 

The micro-casting process is one of the oldest methods for producing many types of article.
Different peoples and cultures used this process to produce tools, objects and statues in bronze. One very famous example is the Bronze Riace Warriors that were salvaged from the sea in 1907, 2500 years after they were made in Greece in the sixth century BC.
The process developed over the centuries, evolving from a simple artistic method and demonstrating exceptional versatility.
Micro-casting, or lost wax casting, has been used for many years in the automotive and aerospace technology sectors, however, this process, although highly reliable, still presents defects.  

In the jewellery world, the most common and problematic defects are:
– incomplete filling of the cast
– porosity by retraction.
While cases of the first type of defect are limited to specific kinds of production (filigree, particular alloys, complex geometries…), the second can be found in all micro-cast products because it is intrinsically linked to the solidification process of the metal alloy.

It is on this latter category of defect that we will be focusing our attention.
Up until a few decades ago, “Trial and Error” was the obligatory method of trying to solve the problem of porosity by retraction.
With practice and experience, the aim was to minimize and hide the defect.
In order to obtain a commendable result, modest amounts of time and metal needed to be invested.
Simulating the process in a virtual environment minimizes this investment and achieves a better result in less time.

Nowadays, simulation software has reached a high level of precision so that excellent results can be obtained in terms of product development times and the production process can be improved.
The use of casting process simulation software in the jewellery sector is relatively recent although it is constantly on the increase due to the growing request for quality on the part of the big jewellery companies.

Simulation software works when there is a deep knowledge of the entire process. For this reason, the more it is used, the more information will be available to configure the process and the more the results provided by the software will correspond to industrial needs.

The software used for this study is produced by the French ESI Group and is called ProCAST.
It is an advanced and complete tool and has been on the market for over 20 years. It is widely used in various industrial fields. The software is based on finite element technology and is able to simulate a long list of real processes. This study focuses on the module for simulating the lost wax casting process.

A knowledge of metallurgy and the production process is necessary to be able to use the software to its best advantage. With the help of the SW, the process technologist can work out the best conditions for a reliable and robust micro-casting process.

The software consists of the following environments:
– MESH
– CAST
– VISUAL

MESH is the environment in which our object, starting from the CAD model, is broken down into minor elements (mesh) that the then software uses to understand the points on which to calculate the thermal exchange and solidification equations. The operator decides on the size of the mesh in accordance with various factors. Besides the object of our study, the mould into which we will be casting the metal in order to accurately simulate our process must also be designed and “meshed”.

CAST is the environment where all the parameters to be taken into account in our process are inserted: type of alloy, process temperature, pressure of the metal as it goes into the mould, entry section, thermal exchange, radiation phenomena, etc…

VISUAL is the ideal environment for observing and measuring the simulation results and, depending on what is being analysed and measured, different physical measurements can be viewed (temperature range, solid fraction, voids, porosity, flow speed, etc…)
With the help of Procast, it is extremely easy to foresee where the defects of a particular micro-cast will be and how large these defects effectively are.

Thanks to the software, we can quickly and fully investigate the porosity by retraction defect.

The problem of porosity by retraction is strictly correlated to the solidification concept. In fact, porosity by retraction occurs when the metal status turns from liquid to solid: the metal undergoes a volumetric contraction and, where the volume retracts, dendritic structures, which can become larger as the alloy hardens, can emerge on the surfaces.

Dendrites are tree-like structures that form during metal alloy solidification. The metal forms crystals that grow and solidify in the most energetically favourable crystallographic directions. If cooling is fast, dendrite growth is limited. On the other hand, if cooling is slow, the dendrites will be larger and, in the worst scenarios, visible to the naked eye in the volumetric retraction zone.

Volumetric contraction is intrinsic to the solidification process and therefore, porosity by retraction is an inevitable defect in the casting process.
Porosity by retraction cannot be eliminated but it can be conveyed to strategic points by encouraging directional solidification.

When a metal alloy solidifies, the last volume to do so, that is, the one that stays “hot” the longest, will be the part that contains porosity by retraction.
In designing a casting system, it is therefore essential to study the thermo-dynamic factors that lead to controlled solidification: the casting channels, feeders and risers are to be designed and sized so as to be able to correctly feed the piece being produced and, at the same time, “keep” retraction out of the areas of interest.

To study the solidification of micro-cast objects, it is important to consider the cooling module.
The cooling module, or thermal module, is given by the ratio between mass and surface of an object M=V/S.
Starting with volume, if the surface of the object is greater, solidification time will drop drastically. Solidification time depends on M and also on the type of material and the object’s geometry.
Studying solidification time is essential for shifting the direction of solidification. 

Let’s take a very simple object, such as a wedding band, for example.
Being circular and symmetrical, the point in which we put the feeder is of no importance. What is important, however, is the feeder’s section and geometry.
Below is an example of the solidification simulations of the same ring with three different feeders in ascending section size.

As can be seen in the picture above, the feeder with the largest section tapered towards the metal entry section is the one that fills the cast and directs ring solidification correctly. 

As further evidence of the correctness of feeder 3’s design, we can see, again by simulation, a reduction in porosity (in purple) in the diagrams below.

Now let’s look at another simple ring geometry, but this time with a variable section.

In this case, since the geometry is not symmetrical, the point at which we feed the ring is of fundamental importance. Figure 7 below shows the progress of solidification based on the point chosen for positioning the cast feed.

Solidification observed in the previous figure leads to porosity in the areas highlighted in figure 8.

The results can be verified by observing the actual components cast. When using simulation software, it is extremely important to calibrate the reliability of the software with one’s own casting process.  
The photographs below show the surfaces of the ring analysed and cast with the two different feeder positionings:

Similarly, taking a larger object, we can see that the same directional solidification rules can be applied in this case too.
The figure being examined is a “C” which could be used to make half a bracelet.

In the first example, let’s consider the item with the same type of feed but cast with different parameters. The response variation to the change in temperature, both in the mould and in casting, is particularly notable.

As can be seen from the diagrams, as the temperature rises, the size of the porosities decreases. This happens because the metal is given more time to solidify in a directional manner. In this case, however, only modifying the process parameters does not solve the problem at the root.
It is therefore necessary to modify the feed. Let’s look at two different feeds.

The figure below shows the simulation of the solidification process in both cases.

Analysing the figure on the left, it can be noted that the six feed spokes are solidifying before the bracelet itself has solidified (as in the previous example), thus “blocking” the way for the metal to continue to feed the object correctly. In the figure on the right, however, we can see how the four spokes are feeding the piece well, resulting in a directional solidification towards the heart of the column.

Evidence of the efficiency of type B feeding position can be given by analysing the porosity.
In figure 16, it can be noted how, in case B, the object has no porosity, while in case A, there are six porosity nuclei exactly where the metal took longer to cool.

The accurateness of these simulations is shown in the photographs below.

The analysis of these simple geometries demonstrates the validity of simulation. The software can precisely predict which areas will be affected by defects and their size.
The micro-casting simulation process is a useful tool for the technologist who cannot totally eliminate the “Trial and Error” process but can limit it in the virtual simulation environment, thus reducing product industrialization times and costs.

The fundamental tool for using casting simulation software is CAD 3D modelling.
In fact, as already mentioned, in order to be able to simulate the casting process, it is absolutely necessary to start from a 3D model of both the casting system we want to simulate and the mould in which we will be casting the metal.
The more accurate the initial model is, the more accurate the simulation results will be.
Moreover, CAD modelling offers the advantage of being able to rapidly design and simulate various types of feeding points and casting systems.
By simulating different feeding points, we can find the best one for our item.
By carrying out casting simulation at the beginning of the design process, it would immediately be possible to identify errors in the design and intervene by modifying the model’s geometry.   
If modifying the item is not possible, then acting on the other parameters (feeding, process parameters, etc..) will become necessary.

Once the importance of simulating each individual detail has been understood, new possibilities for more complex casting systems can be explored. By simulating an entire casting tree, for example, it is possible to analyse the entire process and optimize it.

In conclusion, introducing this technology into the jewellery supply chain is undoubtedly helpful for moving towards better production performances and benefits companies that want to use additional forces and means in their production processes.

Resources and study are needed to take best advantage of this technology. Nevertheless, the benefits resulting from its usage (savings in time and means as well as the effectiveness of the results obtained) eliminate every uncertainty. In time, this will be the only way to proceed in jewellery industrialization, as has already happened in other production sectors.

a speech by Antonello Donini

We are talking about

SYNTHETIC DIAMOND

Crystalized carbon (C) in the cubic system and arranged tetrahedrally within the grid.

As with natural diamond, this configuration gives the material properties that make it unique. 

Therefore, we are not speaking of an imitation but of an authentic diamond produced by artificial synthesis methods made by man rather than by nature.

Initial attempts to produce the exact synthetic counterpart of diamond in the laboratory date back to the late 19th century, although the first historical success was recorded in the early 1950s when researchers at the American company, General Electric, synthetized the first small diamond crystals.

About 20 years later, General Electric was also the first to create synthetic diamonds large enough to be used as gems. This success was followed by the Japanese company, Sumitomo, and De Beers in the 1980s and by Russian laboratories in the ‘90s. 

Synthesis methods

The HPHT production method

This method is based on the conditions that led to diamond formation in nature, i.e. high pressure and high temperature.

Crystal seeds, a metal alloy/solution (e.g. nickel and iron), which acts as an amalgamate/catalyst, and the nutrient (usually graphite) are placed inside the reaction cell and exposed to high pressure and high temperatures (between 1400 and 1600° C and between 50 and 60 kbars) using heating elements and presses.
The carbon dissolves into the amalgamate and then deposits on the crystal seeds in diamond form, usually in a part of the cell where the temperature is lower.

HPHT method  BARS

HPHT method  TOROID

HPHT method  CUBOID

An important problem to face in this synthesis method is keeping any nitrogen responsible for the yellow-green to brown colouring of the synthetized crystals at bay.
Using new metal alloys as amalgamates, with the addition of particular elements (such as aluminium, cobalt or copper) fixes the nitrogen so that it cannot go back into the diamond grid.
Colourless diamonds (like lla diamonds) or those with a slightly bluish colour due to a very slight quantity of boron (type Ilb), are thus obtained.

CVD SYNTHETIC DIAMONDS

This method has the advantage of taking place at low pressures of about 10-200 torr.
A plasma is created in the chamber that breaks the molecule of the methane or other carbon-containing gas.
The carbon is then deposited in diamond form on a substrate usually made of tiny diamond seeds.

Useful identification elements

Colourless, CVD synthetic diamonds are generally of the Ila type, i.e. purely carbon.

In order to eliminate any possible brown components in crystalized diamonds that may occur with this method due to dislocations, the stones are subsequently subjected to an HPHT treatment which can eliminate them. 

Under the microscope, synthetic HPHT diamonds often show characteristic growth shapes, correlated to sectors of cubic and octahedral growth.

This growth can be found in zonings of various fluorescence or in the colour distribution within the stone that follows these growth sectors.
Characteristic inclusions, not always present, are amalgamate residues  that look like black and opaque inclusions with a metallic shine.

Characteristic inclusions, not always present, are amalgamate residues that look like black and opaque inclusions with a metallic shine or large groups of punctiform inclusions (probably minute particles of dispersed amalgamate).

CVD synthetic diamonds can have minute, dark inclusions (carbon residues) with tension streaks probably generated by subsequent heat treatment used to improve the colour of the gems.

Many HPHT synthetic diamonds have a typical fluorescence that ranges from yellow to a yellowish green under UVL (365 nm) and UVC (254 nm).

The impurities that are absorbed in the synthetic diamond structure during its growth tend to concentrate in particular growth sectors, that is, they generate characteristic cross-shaped or octagonal fluorescence shape, that are not found in natural diamonds.

Unlike natural diamonds, the reaction is more intense at short wave than long wave.

Natural diamonds generally show a variable degree of quite uniform blue fluorescence (yellow is much rarer and green or pink even more so) which is, in any case, more noticeable at long wave than at short wave.  

The usually persistent presence of phosphorescence (extremely rare in nature and atypical in colourless stones) is a good identification sign.
In fact, llb-type diamonds are extremely rare in nature (containing boron) which only usually have this effect for a short time.

A particular characteristic of diamonds produced with the HPHT method is that they have few or only slight abnormal birefringencies, unlike natural diamonds. In CVD synthetic diamonds, abnormal birefringencies are generally similar to those in natural, lla-type diamonds, that is, they have a kind of trellis, often going in the same direction as the crystal deposit. 

There are, however, CVD synthetic crystals with an «optic» quality (THEREFORE OPTICALLY PERFECT AND HOMOGENOUS) with no abnormal birefringencies.

Definite identification is only possible with advanced analytical techniques

Infra-red spectrophotometry is ideal for helping to recognize the type of diamond, or rather, to check for the presence or absence of traces of some fundamental elements. IRS thus has the potential information for isolating diamond types that could be compatible with synthetic production.

Colourless synthetic diamonds are type lla (nitrogen in such small quantities that it cannot be detected instrumentally with IR), while blue diamonds, like their natural counterparts, are type llb (presence of boron). Type llb, or rather, traces of boron, can often be found in many colourless synthetic diamonds. Pink synthetic diamonds have also been seen on the market due to a subsequent irradiation treatment and heating at low temperatures. It should be remembered that, due to the presence of nitrogen, the initial productions foresaw yellow colouring in various shades of brown or greenish-brown. Some diamonds of this type, treated with irradiation, have been known to become a very bright red.

In UV-VIS-NIR spectrophotometry, the lb component in yellow-green synthetic diamonds generates an absorption that starts at 500 nm and goes towards ultraviolet.
Many diamonds show a series of absorptions, between 470 nm and 700 nm, with a more evident absorption at 658 nm. These peaks are due to the presence of nickel within the crystalline structure in the catalyst.
lla-type colourless synthetic diamonds are transparent up to 270 nm.

The presence of elements like nickel, iron, aluminium, cobalt, copper or other metals used in the growth, can be identified through chemical analysis with X-ray fluorescence (EDXRF).

Centres of diagnostic colour can be detected through photoluminescence due to traces of impurities. In this way the synthetic nature can be recognized.

Observing the effects of luminescence under extremely short uv can be very useful in recognizing synthetic diamonds.    

Overview of the market situation

Synthetic diamond producers claim that:

Lab-grown diamonds essentially have the same chemical composition, crystalline structure, optical and physical properties as diamonds extracted from mines: they are, therefore, 100% diamonds. The only difference between synthetic and mined diamonds is that one was created within the Earth and extracted while the other was created in a cutting-edge laboratory.

Numerous producers synthetize diamond above all for industrial purposes.

In jewellery, the size of multi-faceted gems has reached decidedly significant dimensions: gems of over 10 ct have been seen.
But the greatest distribution of this product is with gems up to a maximum of 2.00 ct and in melee lots (from less than a dot to up to 0.25 ct).

Constant growth and distribution of this gemmological material in the jewellery sector is towed by its intensive and ever-greater use in industry.
It is widely used in instruments such as super sanders, grinding wheels, cutting tools, tools for drilling and polishing, products used in the automobile, medical, aerospace and electronic industries.

Due to their manufacturing costs and market importance, synthetic diamonds play a leading role in Asian countries, followed by North America.

Commercially-speaking, they are receiving considerable success and distribution in the USA and Japan.

As a detrimental measure against those dealing in the natural stone, the American FTC (Federal Trade Commission, the legislative trade authority) has allowed these synthetic stones to be called “grown diamonds”.
It has also established that «synthetic diamond» is to be considered as real «diamond», thus allowing the synthetic stone producers to market their products as «real» / «true» diamonds.

The rest of the world and the international ISO standards foresee that, for the purposes of clarity and the consumers’ benefit, this gemmological material should only be called  “synthetic diamond” the same as any other type of synthetic product. 
No other definition or simplification is allowed.
ISO 18323:2015

The cost of this material is currently 30-40% lower than natural stone but further reductions are foreseen due to its ever-greater distribution and a reduction in production costs.

Synthetic diamonds currently represent about 2% of the global market.
It is expected that, by 2030, this share will have risen to 10%.
For stones that weigh around 0.50-1.50 ct, suitable to be used as solitaires, that is, for engagement rings, a 7.5% share could already be reached in 2020.

The share could reach 15% in the next two years for «melee».

The distribution of this material in melee could be intensified by a progressive scarcity of diamonds extracted from mines, since the Argyle mine, which currently supplies the majority of the world’s small diamonds, is soon to be closed (almost totally exhausted).

It is therefore difficult at this moment in time to predict exactly how this material will affect the jewellery market.

From marketing studies, it would seem that new generations are positively in favour of using this new material in personal ornamentation.

The diamond is losing its appeal as a symbol of rarity and eternal love and is becoming a highly common gem.
Consumers are beginning to see synthetic diamonds as desirable: they can have much larger gems at lower prices and, above all, make an investment «without feeling guilty».
Considerable media campaigns to publicize these gems as much more ‘ethical’ than their natural counterparts, are underway. 
The younger generations, rightly oriented towards the environment and the non-exploitation of natural and, above all, human resources, are showing greater interest in this type of gem compared to past generations, who were more greatly concerned about the uniqueness and rarity of each jewellery item.

Big names from the entertainment and web worlds, such as Di Caprio, Lady Gaga, Penelope Cruz or the owners of Facebook, Twitter and eBay, have publicized or even financed synthetic diamond production facilities, believing in their future.
The Diamond Foundry, one of the latest US producers to appear on the market, has declared itself as the only producer currently supplying certified «carbon neutral» diamonds, since its stones are made in a hydroelectrically-powered plasma reactor.
The company claims that: “mine extraction has a greater impact on the environment than any other human activity. For every single carat of diamond mined, about 250 tons of earth must be excavated and this releases a considerable amount of atmospheric pollution with heavy carbon dioxide emissions.”

Through its LIGHTBOX brand, De Beers has started the on-line sale of a line of colourless, blue and pink synthetic diamond jewellery at a much lower cost, trying to secure a significant share of the global market (1.00 ct 800.00 US$ – 0.50 ct 400.00 US$ – 0.25 ct 250.00 US$).

More than 60% of those interviewed in studies would be willing to buy, or interested in buying, a synthetic diamond for an engagement ring due to the lower cost of the material which would allow them to have a larger stone at a lower cost.

Consumers with financial resources, traditionally more bound to the charm and mysticism of the unique and unrepeatable … now seem to be showing a lot of interest in this material.

Synthetic diamond producers have been able to arouse the interest of the so-called «millennials» by promoting Lab Grown Diamonds as high-tech, innovative and clean.

In every aspect of their lives, Millennials look for brands, companies and products that they believe to be transparent, social and respectful of the environment.

Nowadays, consumers no longer believe in the value of diamonds or of jewellery in general.
In fact, several factors have spread mistrust in the sector over the years.

• Traders that lack transparency
• Traders with a poor knowledge of the materials and market
• Poor investment yield on diamonds
• Few certainties

We must, however, bear in mind that: a natural diamond, even if poor in quality, will always have a potential buyer.
There is, on the other hand, no secondary market for synthetic diamonds, especially since diamond traders currently tend not to deal in them.
The «good bargain» aspect, or rather, the savings made on buying a synthetic diamond, becomes less tangible when you consider the fact that it will not be possible to re-sell it.

At the moment, the outlook is decidedly confusing and unclear.
World traders, given the economic interest that rotates around the natural material, are decidedly concerned and scared about the sudden distribution and by the number of media campaigns that feature synthetic diamond.

But, if we look at the past what is happening now was promoted in exactly the same way before when, at the beginning of the last century, DeBeers, through targeted media campaigns and movie stars (we could mention Marylin Monroe and phrases like «diamonds are a girl’s best friend» and «diamonds are forever»), disseminated the use of diamonds in jewellery so that they could become a «symbol of true and eternal love» for everyone.

It is therefore hard to answer the initial question but perhaps we could now pose another: “could synthetic diamond be an opportunity?”