Memories archieve

Jewelry and direct 3D printing: the start of a new era?

As part of the fourth industrial revolution, direct printing of precious metal jewellery deserves constant analysis of the current state of the art to understand whether and when a jeweller should favour this technique over classic lost wax casting methods. In recent years, our research programme has included studying printing strategies, support techniques and a general analysis of the chemical and physical characteristics of the precious powders used. With this study, we are looking at technological evolution with a more practical and operational eye, sharing our experiences and giving an honest analysis of both the good and bad aspects of 3D jewellery printing, trying to define when and why it is convenient to print jewellery items.

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How can digital technologies and craftsmanship provide solutions for the heritage sector?

Museums have a delicate balancing act. As public institutions they have a responsibility to preserve and protect our cultural heritage, while simultaneously, providing access to their collections for scholars and members of the public.  This paper will consider the opportunities a blended approach of technologies (traditional and new -laser scanning, CAD, 3D printing and craftsmanship) can provide to bridge these conflicting demands. 

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Jewellery : Is it fit for purpose? An analysis based on examination of customer complaints

In the UK, if a customer has a complaint about the quality or performance of their jewellery, the retailer can send it off, often via his Association, The National Association of Jewellers, for an independent examination by a technical expert at the Worshipful Company of Goldsmiths (who also run the London Assay Office). The expert examines the item of jewellery and makes an assessment of the problem (damage and defects) and its probable cause. He also indicates where he considers the blame lies – the customer, retailer or manufacturer. This helps to resolve the dispute.

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Dos and do nots of online retail: personal data protection vs profiling

Online retail is constantly increasing, tracking technologies have evolved considerably (e.g. mobile device tracking, augmented reality, social networks, data mining, cloud computing) and personal data of the Internet users are extensively used to provide customized products and services or as currency in exchange for services. A better access for consumers and business to online goods is one of the pillars on the digital single market strategy of the EU Commission: behavioural tracking is often perceived as a threat to privacy, but it may also be a potential competition issue with reference to exchange of competitively sensitive information. The speech will comment the legal framework concerning online behavioural tracking, and in particular Regulation 679/2016/UE (GDPR), Decree 196/2003 (“Codice Privacy”), e-Privacy Directive (and the related amendment proposal published on January 2017) and the decision of the Italian Data Protection Authority held on May 8th 2014 (“cookie law”) in order to share with the participants a set of guidelines for legitimate profiling.

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Electro Sinter Forging: a Superhero of Powder Metallurgy

The production of jewellery and components traditionally relies on a wide range of production methods that goes from typical artisan techniques to the sophisticated procedures used in industrial manufacturing. In recent years, powder metallurgy (PM) techniques have been increasingly adopted, even alongside traditional metal-processing methods. In particular, and in the broad sense, the jewellery sector has turned to PM techniques to alleviate design and dimensional control problems that can arise, for example, with traditional casting methods. In this perspective, Metal Injection Moulding technologies and metallic Additive Manufacturing techniques (Selective Laser Sintering, Selective Laser Melting, 3D printing) have been attracting a great deal of interest. Powder Metallurgy is still an extremely vast field of study that is leading to progess, not only in terms of design, but also in terms of optimizing material and energy consumption - its traditional function - and, above all, in metallurgic terms. Considering these factors, the technques classified under the acronym FAST (field-assisted sintering techniques), i.e. those field-assisted sintering techniques that lead to a rapid powder consolidation process, as the acronym suggests, are extremely interesting. This work outlines a specific FAST, Electro-Sinter-Forging (ESF) technique which shows, through practical examples, the advantages that can be obtained in terms of process speed and component precision from advanced mechanical properties, thanks to the possibility of obtaining micro-structural and compositional conditions that cannot be obtained by applying traditional techniques.

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A Study of the Effects of Digitally Produced Casting Models on Casting Quality

Today’s jewelry manufacturers are incorporating digitally produced casting models into their production processes at levels never seen before. Machine costs have dropped dramatically, and makers now have a wide variety of 3D printers and materials from which to choose. None of these are qualitatively identical, and there is a significant body of evidence, both anecdotal and documented, indicating that materials used in digital production have varying degrees of success in investment casting. The root causes of related defects are not fully understood, leaving the industry plagued by speculation and a variety of home grown methods aimed at addressing these problems. Through the use of controlled studies, we first explore the burnout behaviors of several mainstream materials, followed by an evaluation of dimensional movement experienced by these materials when subjected to investing and firing. Casting defects will be tracked to their root causes through dimensional analyses and observations of defect morphology in cast product.

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Ten hot metallurgy questions! A hitlist of the most common jewelry making metallurgy inquiries and their answers

The present work aims to provide a list of the most common questions made from the customers according to our experience on technical assistance, in terms of information on products (master alloys for gold and silver production) and on jewellery production processes. A particular focus will be given to the answers that were provided and of the implications in the everyday life in production departments.

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Understanding the properties and improving the processing of silver alloys

Silver alloys are widely used in jewelry and are showing some distinct production issues. The paper aims to provide guidelines to the manufacturer of silver products as well as to the goldsmith to achieve high quality products with reduced reject. At first an overview on the metallurgy of silver and silver alloys with a focus on some specific properties of silver, for example the high gas permeability, will be given. These specific properties are the reason for many production problems such as fire scale or different type of porosity. The variation of the silver content in the typical range from 925-935Ag and the role of alloying additions will be highlighted. The metallurgical basis will provide guidelines to the define conditions for the manufacturing of silver products by different processes, such as melting & casting, hot and cold deformation, annealing, quenching, ageing and brazing. Typical failure sources will be identified and illustrated by examples of defective samples. As a consequence the requirements on alloys, equipment and processes will be described and proper working conditions in industrial production as well as in the goldsmith’ workshop will be given.

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A change in jewellery retail

Global connectivity through the Internet is experiencing exponential growth. Sales practices for the more evolved luxury products, based on principles of exclusiveness, speed and personalization, focus on customer service with a buying trail that can be accomplished in both a physical or virtual store through various on-line platforms. The potential buyer is drawn into the brand’s life and increasingly involved in the productive process of the goods being purchased.

With the help of the Boxstylab agency, Biagi analyses both the physical and on-line retail scene as well as integrated multi-channel communication, reflecting on how technological innovations can radically transform the customers’ possibilities and expectations, and how customer-focussed sales strategies have become indispensable competition leverage for companies operating in the jewellery sector.

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Do the new low-cost 3D printers have a place in the jewelry manufacturing environment?€

With the recent ending of a number of patents, along with the burgeoning home 3D printing movement (e.g., Fab@Home, RepRap), a huge and often confusing number of new, low-cost ‘home-user’ or ‘consumer-level’ printers have arrived onto the 3D printing scene. A possibly useful spin off from this for the jewelry industry has been the emergence of a number of, principally but not exclusively, low-cost Digital Light Processing (DLP) systems. Many of these have been developed specifically for, or are capable of, printing in castable resins (photopolymers), which are ideal for use in the jewelry lost-wax investment casting process.

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Improving the Properties of Precious Metals by Heat Treatment€

Heat treatment of precious metal jewellery alloys is often referred to in the literature but many practitioners do not have a clear understanding of what this term means and its importance to the jewellery industry. It is a term often used by metallurgists to describe a range of thermal processes designed to manipulate properties of engineering and decorative alloys to meet requirements. Many will be familiar with heating and quenching of steel to harden it, whilst age-hardening of steels and aluminium alloys is an example of a two-stage treatment that is widely used to confer additional strength.

Many treatments involve heating of the alloys to specific temperatures for specified periods of time and then cooling at a defined rate that may be rapid or slow. In jewellery, annealing of precious metal alloys is often undertaken to soften cold-worked material to enable further working without cracking or fracture. But other types of annealing are also carried out, for example to stress relieve alloy items to prevent stress corrosion cracking or to ageharden them. In investment casting, the burning out of casting moulds (‘flasks’) requires a defined temperature and time cycle to enable good castings to be achieved. This is also an example of a heat treatment.

Whilst annealing and age-hardening of jewellery metals has been featured in previous JTF presentations, the ‘whys’ and ‘wherefores’ of such treatments have not, perhaps, been fully explained. There are several types of annealing treatments in use, each with different objectives. This presentation focuses on heat treatments used in the jewellery industry and attempts to explain the underlying principles involved. Examples of heat treatments of base metal alloys are also included to demonstrate that such treatments are universal.

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Study of the microstructure, residual stresses, mechanical and corrosion properties of different gold alloys used in industrial processes

Gold alloys, used in the production of gold chains, affect the optical and mechanical properties of various gold products. In fact, the corrosion resistance and the workability of the chains depends on these properties. It is important that gold alloys with high corrosion resistance do not degrade during the production process. The microstructure of the alloys strongly influences the mechanical properties, which have a key role in both the machinability and quality of the plates. In the present work, different compositions of gold alloys and different annealing steps in the deformation processes were analyzed and optimized. In particular, the choice of the suited grain refiner is very important to avoid particular unwanted behaviors of the gold alloys. The changing of the production parameters and the compositions of the alloys leads to the formation of different levels of residual stresses within the material, which can generate a variation in the behavior of gold sheets. The microstructures were analyzed by OM and SEM observation, whereas the variation of mechanical properties by micro-hardness test. The residual stresses were evaluated using XRD analysis and the corrosion resistance by potentiodynamic polarization tests. The results showed that a high homogeneity of the microstructure and a suitable recrystallization process, with an increase of the quality of semi-finished products, were obtained.

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Strengthening pure gold significantly by no more than 1 wt.% Zr, Ce and Si

Gold is an ancient metal, it can be widely used in the electronics, dentistry and jewelry industry. It is also well known that pure gold has good ductility and very lower vickers hardness. These mechanical properties of pure gold definitely lead to easy deformation, scratch, abrasion and so on when pure gold is put into application. Therefore, it is necessary to strengthen pure gold by micro-alloying to avoid Its obvious deficiencies and maintain its excellent properties such as yellow color, good thermal conductivity, chemical stability.

Our group chose Zr, Ce and Si as the micro-alloying elements, which are no more than 1.0 wt.%, to strengthen pure gold. The investigations showed that Zr, Ce and Si can strengthen pure gold significantly at as-cast from 30HV to 69HV and wrought state to 121HV . In this presentation, we share the investigation to show how Zr, Ce and Si modify pure gold in structure, thermal characteristic, mechanical properties and what the distributions of different phases and elements are. We also present how the new gold materials can be used in jewelry industry.

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Additive Manufacturing of 18-Karat Yellow-Gold alloys

The present paper describes the results of a collaborative research project on the selective laser melting of 18-karat gold alloys. Three main objectives were pursued during the project: (1) to analyze the effect of the process parameters, (2) to investigate the role of powder treatments and alloy composition and (3) to identify design rules for additively manufactured jewelry items. The laser power, the layer thickness, the scan rate and the overlap of the scans were optimized in order to reduce the porosity of the parts built in 18K yellow-gold alloy. The production of defect-free parts in gold, silver or copper alloys is challenging due to their high thermal conductivity and their high reflectivity for the infrared laser light. Therefore, the alloy powder was slightly oxidized to form a partial oxide layer of several tens of nm thickness. A significant reduction of porosity was achieved with the oxidized powders compared to the untreated powder. Another way to reduce the reflectivity and the thermal conductivity of the powder is the alloying with certain elements. A series of alloys that contained additions of Fe, Ti or Ge showed reduced reflectivity and thermal conductivity.

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High-Tech ceramics on jewellery: processing and applications€

High-tech ceramics (HTC) are becoming common in jewelry pieces. It comes from their exceptional properties that are noble in terms of mechanical properties, corrosion, aesthetical, among others. Although these materials are considered to be difficult to deal with, mainly processing, sintering, machining, polishing, etc, there are some steps that may allow it to be used by a common jeweller in it’s bench. This paper will present the steps that are common in the processing of high-tech ceramics manily, ZrO2 based ceramics. Sinthesys, mixing, coloring, pré-sintering, machining using computer numerical control (CNC) millers and/or manual machining (files, drills, etc.), final sintering and polishing. The importance of some parameters that are relevant on processing of these materials will be presented. It will present the main challenges and provide information about how to deal with the difficulties to process such materials. Examples of final components will be shown. A few considerations on design of jewelry components that contain high tech ceramics along with gold will also be presented.

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3D direct metal printing: a trip through new opportunities and innovative alloys

Direct metal printing changes the rules when creating innovative jewels. Selective laser melting (SLM™) enables researchers to become creative and use new materials. This research tests different, new products, exploring new SLM horizons using incredible materials for gold-working applications.

Additional manufacturing through selective laser melting creates the opportunity to combine materials with thoroughly different properties, in ways that would be impossible otherwise. What incredible new possibilities can we expect while learning from the surprising properties obtained?

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RJC Chain of Custody, our experience

In March 2012, the Responsible Jewellery Council (RJC) published the “Chain of Custody” (CoC) standard for the precious metal supply chain.

The aim of this document is to guarantee the “responsible origins” of all material made and machined during internal and external production processes along the entire chain of jewellery creation. “Responsible origins” refers to conflict-free metal, produced, transformed and transported responsibly at every stage of production, from the mine to the refiner, jewellery maker and on to the store and the end customer.

In 2015 Bulgari Gioielli was awarded CoC certification. This article illustrates our experience in the metal chain of custody.

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Design and Production of digital jewellery: the parameters for innovation

The digital revolution is evolving quickly, changing the rules of the game for production, communication and commercialization of goods at an international level.

Jewellery has become the focus in the new maker scenario, as experimental products feature spectacular shapes, rich openwork patterns, algorithms able to create forms that weave together into convoluted, complex shapes and structures that could never have been made before. These objects have been engineered down to the finest details and reflect the immense potential for innovation, but often fail to become genuine pieces of jewellery.

In this presentation, Beatriz Biagi explores the potential of new technologies for the design and production of jewellery that can be a valid answer to the needs and expectations of the end customer. Analysing the product and commercial trends, Biagi looks into the design parameters and critical elements to be considered in Jewellery Design. 

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Presentation of a new acid-free refinement process for gold and silver

The cutting-edge refinement technology, known as ACIDLESS SEPARATION® (ALS®) comes from close collaboration between IKOI and Ekaterinburg Non Ferrous Metals Processing Plant (EZ-OCM).
This technology makes it possible to pre-refine doré and jewellery alloys with the prerogative that the process is extremely efficient, even with a high silver content, which is normally a problem for existing chemical pre-refinement processes.
ALS® does not require the use of acids or toxic substances, which is a practically unique feature compared to current refining systems. It is to all intents and purposes a green technology.
Compared to the panorama of traditional refining methods, it can be seen that the technology being presented guarantees a high degree of flexibility as it is not bound to the chemical composition of the alloy being treated.
After intense research and development, the process, which is based on the vacuum distillation principle, has made it possible to achieve excellent results in terms of selectivity and productivity, while at the same time guaranteeing a practically zero drop in precious metal mass .
The process, which stands out for its excellent scalability, is flexible when it comes to meeting different production capacities, ranging from the refineries in a medium gold industry, through to the large-scale precious metal refineries treating doré alloys downstream of mines or industrial precious metal waste.

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Implementation of the UNI EN ISO 9001:2008 quality control system in a gold industry SME

Application of an integrated system to meet quality standards with regard to processes. Traceability of materials, ethical requirements and respect for the environment.

A company case history that highlights how company problems, critical issues and inefficiencies have been corrected and managed via a system to monitor and control company processes.

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The Effects of Hot Isostatic Pressing of Platinum Alloy Castings on Mechanical Properties and Microstructures

In earlier research a better understanding of the solidification characteristics for a number of platinum-based alloys was established. The findings demonstrated a strong tendency toward the formation of shrinkage and gas porosity upon solidification, and hot isostatic pressing (HIP), a high-pressure thermal treatment developed as a densification process, was proven to be an effective method to minimize and/or eliminate this porosity.

While the previous results made it clear that porosity had been significantly reduced following the HIP process, the authors had not yet explored the full range of HIP’s effects in terms of post-processed microstructure and mechanical properties. The goal of this new phase of research is to further our understanding by characterizing the post-HIP effects on platinum based castings with respect to grain size and shape, chemical distribution, and mechanical strength. 

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Investment casting of Ti alloys by induction melting

The casting of titanium based alloys is a complex and expensive procedure, due to their high melting temperature and chemical reactivity with oxygen at T > 600°C. Hence, molten titanium easily reacts with crucibles and mold components during casting. Therefore, the whole process is done in vacuum or inert gas atmosphere, e.g. in cold crucible arc casting machines under argon atmosphere. However, conventional techniques can be also used for titanium casting, but require some adjustments regarding crucible and investment material. A couple of crucible materials are commercially available with supposedly suitable properties for titanium casting. The aim of this study was to assess the suitability of selected commercial ceramic crucibles for the investment casting of Ti6Al4V for jewelry purposes. A commercial vacuum tilt casting machine and a centrifugal casting machine were employed to cast the alloy in copper molds or in refractory investment shells. The form filling of the shell, the crucible and the investment reactions were assessed by microstructural investigation, chemical analysis and hardness profiles of the as-cast items as a function of shell temperature. The reaction of the alloy strongly depended on the crucible material, the coating of the crucibles and the temperature of the ceramic shell. Optimum results were achieved with yttria and yttria coated alumina crucibles. Improvement of the materials and process costs are necessary to allow the competitive casting of jewelry made from titanium alloys.

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Technical requirements for the application of the optional assay mark

As defined in art. 34, comma 5 of DPR no. 168, 4 August 2015, the company can request a test of the conformity of its products and the affixing of the conformity mark “Italia Turrita” at the competent Chamber of Commerce, which will be served by an accredited Laboratory (ISO/IEC 17025)  or a national accreditation body (Reg. EC no.765/2008) for the certification of purity of precious metals.

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New aspects in italian law concerning the regulation of fineness and hallmarks for precious metals

The current Italian standards regulating fineness and hallmarks for precious metals (Lgs. Decree no. 251, 22 May 1999, and D.P.R. no. 150, 30 May 2002) was unfortunately already outdated at its creation.

This is due to thee very nature of the delegate legislative measure (ex art. 76 Cost.). In this case in fact, the new regulation cannot exceed the limits of the parliamentary delegation (the result would be a declaration of anti-constitutionality “through excess power” on the part of the Constitutional Court).

In the case in hand, proxy was granted by Art. 42 of law no. 128, 24 April 1998, containing “Provisions for the fulfilment of obligations arising from Italy’s membership of the European Community - Community Law 1995 - 1997".

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Optimization of SLM Technology Main Parameters in the Production of Gold and Platinum Jewelry

In 2013 we studied and improved the quality level of the parts of jewelry pieces. Our effort was aimed at obtaining jewelry pieces through selective laser melting (SLM) with a quality level similar to investment cast pieces. This development work enabled us to obtain higher accuracy levels for gold alloys. This aim was reached with the use of parallel laser scanning, with a double laser scan and with the selection of optimum laser scanning parameters to avoid the well-known formation of surface-swelling defects. The addition of gallium was shown to increase the formation of this defect as well.
Moreover, in this experimentation we evaluated the effect of the structure of the support system of the pieces, namely shape, density and slope angle of piece walls. We used the optimum work parameters selected in preceding experiments and studied the effect of some elements favoring the absorption of laser radiation (Ge, Si, Pt). Thus, surface swelling, ejection of metal particles and surface roughness of the pieces were reduced.

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Traceability of production processes: from microfusion to the finished product.

Useful methods for monitoring and controlling the transformation process for checking production flows internally and along the supply chain as a whole.
The proposed model aims to rationalise and map out the production stages, isolating any causes of error in determining ownership and identifying the origin of raw materials.

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Three-dimensional Branding

This talk will deal with the subject of “Three-dimensional branding” and specifically, the way it can be applied to the gold and jewellery sector, its application to jewellery, and its relationship with other safeguards, such as registered designs and copyright, in the light of current regulations and standards and of recent national and EU legal interpretations.

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Implementation and development of e-commerce within the manufacturing context of gold and silver working: the case of Better Silver

By implementing an e-commerce site (www.silver-retail.it), Better Silver has taken the opportunity to create a direct relationship between manufacturer and the retail market, seeing to “cut out the middle man” or in other words, the traditional lengthy distribution chain.  Through a group company, Easy Silver srl, Better Silver, which has been manufacturing out of Vicenza since 1977, decided to face the challenge of e-commerce from 2007.
The choice immediately fell in the direction of a B2B site, dedicated to operators in the independent retail trade rather than opting for a B2C.
Seven years on, silver-retail.it has almost 9000 registered users with more than 1000 active clients, and it aims to become a platform that can be used not only for the sale of items made by the parent company, but also a useful marketplace for others in the industry wanting to enter the complex digital market.

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Platinum investment casting: material properties, casting simulation and optimum process parameters

Platinum is a challenging material for casters because of its physical properties. Several casting studies were presented in recent years. This paper provides a deeper understanding into the casting process by highlighting different aspects. The work started with an analysis of the material properties of several crucibles, different investment materials and two alloys to provide the basis for the simulation of the casting process. The simulation results were used to compare different tree setups suitable for centrifugal and tilt casting. They were critically compared with the results of instrumented casting trials with in situ recording of the melt and flask temperatures. The role of various process parameters such as the type of casting machine, melt and flask temperature, alloy, investment and tree setup on surface quality, porosity and form filling of the cast items was analyzed by 3D computer tomography, scanning electron microscopy and metallography. Variations in the alloy compositions were found to strongly influence the casting quality. As a result, optimum process parameters for centrifugal and tilt casting and new promising alloy compositions were identified. Financial support by the German Federal Ministry of Economics and Energy and the industrial project partners is kindly acknowledged.

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Alloys for Costume Jewellery and Fashion Accessories: an introduction to the field

The world of costume jewellery and fashion accessories production is a broad field, which in some respects has similarities with the jewellery sector. The aim of this work is to provide an overview on the world of brasses and bronzes, with reference to the decorative sectors only, in particular those of costume jewellery and fashion accessories. The main categories of these alloys, and their most important properties for the production process, will be identified. The technologies used, the methods of protection against wear and oxidation, and the possibilities for technological innovation in these areas will be outlined.

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The next 10 years: jewellery manufacturing in 2024!

Jewellery manufacturing technology has made substantial progress over the last 10 years of the JTF. In particular, we have seen large growth in the use of machine-based manufacturing and especially in digital technologies – CAD/CAM, rapid prototyping and manufacturing – allied to the use of conventional technologies such as lost wax/investment casting and powder metallurgy. There have also been developments in precious metal alloy technology so that alloys are better tailored to the needs of manufacturing processes as well as giving better performance in service when worn by the customer. Firestain- & tarnish-resistant silvers would be a good example here.

It is appropriate, therefore, to look into the future and explore where manufacturing technology is going over the next 10 years. There is no doubt that digital technologies will continue to have a growing impact but we can anticipate that the current limits of conventional technologies such as investment casting and powder production will be pushed to new boundaries as a consequence. This will place new demands on the machine technology. We can also expect old technologies to rise again with new developments. The motivation will continue to be increased efficiency in both use of materials and yields, leading to a reduction in costs, widening of design opportunities and the customising of design. In addition, the demand for ethical and sustainable jewellery will add to this pressure. Examples include use of biomimetics to produce stronger, more lightweight jewellery in innovative designs, enabled by rapid manufacturing technologies such as the new laser sintering/melting processes, and developments in the use of mixed colours, coatings and alloys to give new design effects and improved service performance

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Optimisation of the Main Selective Laser Melting Technology Parameters in the Production of Gold Jewellery

This paper is a development of the results presented at the 2012 Santa Fe Symposium®. The effect of the most representative variables of the Selective Laser Melting (SLM) technology on the quality of final products is evaluated by means of the design of experiment approach (DOE). The variables taken into account are laser power, scanning speed and thickness of the powder layer.
The aim of this paper is to identify the chemical-physical characteristics of the powder that ensure the best results of the SLM technique. Analysis of the influence of chemical composition and powder particle size distribution on porosity and roughness of the final items is specifically studied. This work describes the progress obtained with SLM technology in the last year, and evidences the importance of optimising process parameters. All presented results were obtained using precious metal alloys.

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Labelling and Marking for Items in Precious Metal - Use of laser technology in the Italian gold industry

Items made in precious metal alloys must provide the market and consumer with all of the information concerning the nature of the main precious metal in the alloy (Gold, Silver, Platinum, Palladium), its standard (percentage in thousands or carats) and the name of the manufacturer or importer (in charge of issuing the item on the market) and, in some legislations, the mark of the controlling body (Assay Office) certifying the authenticity of the item.
If communicated and registered, it is possible to add further markings to identify the manufacturer and/or retailer to the obligatory legal marking (identification mark and hallmark).
This information is stamped onto the item at the end of the production process, using mechanical or laser marking technology.
At the end of the identification process, the item can be legally put on the market.

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Thickness Plating with Nickel-free Palladium alloys

Nickel-free galvanic treatments are increasingly requested, although at times it is very complicated to find replacements for galvanic baths containing Nickel.  This is due either to the increased process costs or to difficulty in managing the processes or more simply, for both reasons. One very widely used treatment in decorative galvanic baths uses Palladium and Palladium alloys. In particular, Palladium/Nickel baths are very popular and less expensive than pure Palladium as well as much more versatile (it can be used to obtain deposits of various microns) and simple to use. For this treatment too, alternatives have been studied in the last few years, but none are as good as Palladium/Nickel.
This publication describes a process to replace Palladium/Nickel, which offers the same level of performance as its predecessor, although it is completely anallergic and also allows for ammonia-free processing.
The result is a bath that as well as being eco-friendly, also offers shiny, white plating, even with high thickness. It is a bath that is easy to manage and allows galvanic companies to replace Palladium/Nickel naturally.

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Assessment of nickel release from production items

In 2011 the new European standard for nickel release was issued and all European states have been aligned with this new standard since 31 March 2013. The information provided by alloy producers are nickel release values “as cast” from items and also from deformed and annealed products.  Jewellery production processes are more complex than this and the release values can differ significantly according to the production and assembly processes used.  It is therefore of interest to be able to assess the release of nickel, analysing the different work cycles.
This paper presents the results obtained by mapping the working cycles (casting, torch welding, laser, oven, moulding, shearing, stamping and cleaning) with the relevant amount of nickel release for different alloys in 18 carat gold, simil-gold and steel used in jewellery manufacture.

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Platinum Alloys in the 21st Century: A Comparative Study

Nearly 20 years after its renaissance as a popular jewelry metal, platinum remains one of the most difficult materials to cast.  Even the most sophisticated and experienced casting operations face challenges in attaining consistently dense castings. This original research takes a close look at the solidification behaviors of several mainstream platinum alloys as well as high pressure thermal treatment of castings to increase density.

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Gold based bulk metallic glasses - hard like steel, moldable like plastics

Bulk metallic glasses, also called amorphous metals, are a new fascinating class of materials with special properties such as a low melting temperature, high hardness and scratch resistance and very high elasticity. Although their appearance is like that of/similar to that of conventional metallic alloys they show some very special properties due to their different atomic structure. They can be thermoplastically formed like plastics at very low temperature and pressed into complex shapes. Compared with their crystalline counterparts, they usually show a higher strength, hardness and a higher elastic strain while the Young’s modulus is lower, which makes them excellent spring materials.
Amorphous alloys have been developed based on many different metals, including gold and platinum. To enable their way into industrial applications their properties relevant for jewelry were investigated in a publicly funded research project together with several partners from industry. A new casting method similar to lost wax investment casting was developed in order to exploit their near net-shape formability. Hardness, wear resistance and tarnishing in different atmospheres were investigated. With an as cast hardness of around 360 HV1, a liquidus temperature below 400°C and an as cast color which ranks it among the best premium white gold alloys, the 18 carat gold based bulk metallic glass alloy has attractive qualities regarding jewelry applications. This article is an updated version of [26].

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The latest developments in Selective Laser Melting technology in the production of gold jewellery

It has finally been ascertained that Selective Laser Melting technology can be used for  producing jewellery from powder alloys and the required standard of quality has been achieved.   
To master the technology, we programmed the production of a series of samples on which a systematic study was then conducted. 
To produce these samples, an 18kt yellow gold powder alloy was used at three different granulometric intervals which, together with laser power, scanning speed and the thickness of the powder layer, was one of the variables in our research. 
The aim was to obtain significant data in terms of wrinkling in the raw state, defectuosity and the physical-mechanical characteristics.
The analysis was carried out following a DOE (Design Of Experiments) approach, not only in order to highlight the effect of each individual variable, but also to show how they interacted.
Lastly, we compared the results with those obtained from samples produced using the lost wax technique.

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White gold alloys and new European directive EN1811:2011 on nickel release: limitations and possibilities.

A new revision of European directive on nickel release will come into force the by the april 2013. The new norm will dramatically drop down the maximum allowed nickel release limit, leading to significant implications for the jewelry industry. This paper aims to provide an overview about how the scenarios will change after the april 2013 in comparison to the existing situation. The paper will also discuss what possibilities for materials and technologies with and without nickel will be able to provide satisfactory solutions to the jewelry market, together with a possible change in the way the white gold production is currently approached by the jewelry industry.

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Property Measurement: What use is it to Jewellers?

In jewellery manufacture, it is recognised that alloys and other materials should meet the needs of the manufacturing processes and that the resulting jewellery should give good service performance when worn by the customer. To ensure these needs are met, it is necessary to know certain properties such as density, tensile strength, hardness, colour, tarnish resistance and precious metal content. It is a balance to ensure that the jewelry meets the needs of being ‘fit-for-purpose’ whilst keeping costs to a minimum, for example by reducing the weight of metal in the piece.
Sometimes we measure the properties ourselves but often we rely on data from external sources such as alloy suppliers and the scientific literature. How much reliance can we place on the values we obtain in property testing? This paper considers the measurement of the properties of jewellery alloys and of actual finished jewellery. It reviews the important properties, how they are measured and what they tell us in terms of their relevance to jewellery manufacture and service performance. Mechanical, physical and chemical properties are considered. The importance of making measurements in accord with international standards and the need for industry-agreed standards for testing of actual finished items of jewellery is emphasised.

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Do you know where your gold comes from? RJC Chain of Custody: providing support for supply chain due diligence.

The Responsible Jewellery Council (RJC) has developed Chain-of-Custody (CoC) Certification to support businesses which wish to provide their customers and stakeholders with independent assurance about conflict-free, responsible sourcing.  A ‘Chain-of-Custody’ is a documented sequence of custody of material as it is transferred along the supply chain. Chain-of-custody systems can provide an important point of differentiation and confidence in the business practices involved in production.  Certification of those systems provides recognisable assurance to customers, consumers and stakeholders against a known standard. This can add value to jewellery products and help protect and enhance jewellery brands.
This session will introduce some of the key drivers for supply chain due diligence, such as the US Dodd Frank Act and the OECD Due Diligence Guidance, and provide an overview of RJC Chain-of-Custody Certification:  key requirements, implementation and potential benefits and its relationship with other industry initiatives.

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Sintering: the applicability of the various powder metallurgy techniques in gold manufacturing

Powder Metallurgy is a technology that has been widely used for some time in several industrial sectors and has recently aroused considerable interest in gold manufacturing, especially when used in combination with rapid prototyping techniques such as laser sintering. The ever increasing availability of metal based and non-metal based alloys with advanced features, supplied in powder form, opens the doors to the use of alternative sintering techniques, borrowed from smelting sectors. This paper, therefore, aims at analysing the various sintering techniques, also in relation to the different materials used, ighlighting the advantages and limits.

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Casting low-weight micro-structured materials : a new materials concept for jewelry components.

The rise of the price of gold originated a demand of low weight products by keeping its volume. Hollow casting is coming again as a good practice for low weight components. However the mechanical resistance of the alloys used in the jewelry field is a severe limitation for the thickness of the components.
It has been recently launched the concept of micro-structured components or materials. Micro-structured components are components where an external skin gives the shape of the final product and the internal part is a metallic structure where small metallic arms are combined with hollow areas. This approach allows the obtainment of low weight components with high mechanical resistance.
Casting of these components/materials is still a challenge in different ways: components design, casting/filling of thin walls/structures or disinvestment of obtained components.
This paper will provide information about this new materials design approach. It will present the main challenges and provide information about how to deal with the difficulties.

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Precious metal microstructures in 3D

That the microstructure of a material is important is a well-known fact. The cause, and possible solution, of a problem that arises while working a precious alloy can be identified by studying the microstructure of the material. An optical stereo microscope is extremely useful in providing a three-dimensional (3D) view of a sample, but enlargement is limited. Furthermore, the most common techniques of micro-structural observation, such as optical metallography and scanning electron microscopy, usually only give a two-dimensional picture. Some techniques that provide a 3D view of the microstructure of a surface are now available but have yet to be widely adopted, especially in the gold sector. The aim of this paper is to show 3D images of the microstructure of some precious materials, like ruptured surfaces, different surface finishings or surface defects, and to highlight any additional information that 3D imaging can offer. Anaglyph images obtained using an scanning electron microscope will be used and the audience will be provided with special two-colour glasses.

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Materials and innovative solutions for the gold sector

In the current highly competitive market, the strategy of portfolio diversification and the consequent acquisition of new markets must be supported by the added value that the use of new materials able to improve the performance and emotional aspect of the product can achieve. Solutions and materials normally belonging to sectors that seem far removed from the gold industry, such as mechanics, automobile and furniture, can prove extremely interesting and provide ideas for highly aesthetic solutions and technologies.  

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Style trends and design with the arrival of the new PLM technologies

The application of new technologies is one of the key elements of product innovation. In the jewellery sector today we are at the beginning of a new revolution,
as it integrates cutting edge technical progress. The selective melting technology is already being used for production of non precious objects and has given the
possibility to improve functional and aesthetical qualities of products. Now it is possible to create gold, silver and steel products taking advantage of PLM direct
manufacturing. In this presentation new style trends are analysed focusing on the aesthetical characteristics, production parameters and the high potential of SLM
jewellery pieces.

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Blue, black and purple! The special colours of gold and other precious metals

Gold is unique amongst the precious metals in having a warm, deep yellow colour. It is also unique in that conventional carat gold jewellery can be produced in a range of colours from red through pink or rose to several shades of yellow, to green and eventually to white simply by varying the amounts and ratios of the alloying metals. More interestingly and not so well-known, it is also possible to produce carat gold jewellery in unusual colours such as purple, black, brown and blue. Gold jewellery with such colour effects is commercially available and becoming increasingly popular. It is also possible to obtain interesting colours in platinum and palladium jewellery. Some of these exotic colours are obtained by alloying gold with certain other metals to produce special alloy structures known as intermetallic compounds..The other colours are obtained by forming oxides or patinas on the jewellery surface by cemical or thermal treatments, similar to those used to colour cast bronze sculptures, or by coating the surface with thin layers of other materials. In the jewellery industry, there is some mystery in how such unusual colours are produced. It is not easy to find a ready source of information covering this topic. It is useful, therefore, to review the technologies involved in producing these special colours in precious metal jewellery. In presenting this paper, the focus is naturally on gold but I will make reference to the unusual colours that can be obtained in the other precious metals and also highlight other potential approaches to broaden the range of colours for jewellery (and watch) applications that may emerge in the future.

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Casting Lightweight Hollow Jewelry Using 21st Century Technology

Using investment cores to cast hollow objects with the lost wax method is certainly not new, it has been practiced for at least 5500 years. The recent rise in precious metal prices has caused renewed interest in hollow casting to produce attractively large yet lightweight jewelry. This paper will discuss historic practices for hollow casting and how recent technical innovations collaborate to reduce the difficulty experienced in the past, while expanding the design possibilities that make cast hollow jewelry an attractive alternative in the current market.

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Evaluation of new decorative coatings obtained by reactive sputtering for jewelry applications-Comparative study of abrasion and tarnishing resistance

New decorative coatings offer a substantial opportunity to improve aesthetics on jewelry components. In order to apply new coatings in jewelry field abrasion and tarnishing resistance are basic requirements. However resistance to abrasion and to tarnishing of the new PVD coatings is still far from being studied for jewelry components. This paper is concerned with abrasion and tarnishing resistance of interference colors in transparent coatings (Me-Ox), as well as of intrinsic colours based on Me-NxOx and dark Me-NxOxCx coatings. All coatings were obtained by reactive sputtering. A comparison of traditional coatings obtained by electroplating (gold and rhodium) and the new coatings will be made. Color change on all coatings will be assessed under common jewelry abrasion and tarnishing conditions.

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Direct casting of resin by rapid prototyping: the importance of a scientific approach in creating quality products

In recent years, the gold and jewellery business has shown a gradual interest in rapid prototyping techniques as an element that could meet increasingly extreme design requirements. Although direct casting models can already be produced with rapid prototyping, this potential is not yet being taken full advantage of. The reason could be the lack of detailed information on the materials and the correct processing and treatment techniques. Understanding the characteristics of the material, in fact, plays a vital role in achieving a high quality product. The difference between one resin and another mainly lies in their chemical composition. There are products on the market that range from resins that are very similar to waxes to entirely plastic products but they can typically be distinguished by their greater or lesser propensity for direct casting. A number of studies have been conducted in the past on production parameters, the development of materials able to adapt to the properties of resins and the search for “tricks” and practical indications for processing them. It is, however, necessary to make an even further assessment of the criticalities, not only in the production phase of resin models (slicing and model orientation, accuracy, UV reticulation) but also throughout the entire productive cycle (especially during cylinder baking). Moreover, other external factors that can influence the reaction of the resin are to be taken into consideration, like aging, packaging, cleaning, etc… Lastly, another aspect to bear in mind concerns resin dilation during cylinder baking. Therefore, the chemical-physical characteristics of the material used must be assessed due to their considerable effect on the final results in terms of casting quality. The aim of this work is to analyse resins for rapid prototyping with a scientific approach, firstly by gathering the relative information on the thermal, physical and mechanical behaviour of the material and then by putting this acquired knowledge into practice, correlating the characteristics of the material and the correct procedure to use.

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Platinum Solders: Proper Use and Application in Jewelry Making

There are several different kinds of platinum solders in use today. Some contain up to 95% platinum, other contain no platinum at all. Each vendor tries to have their own mix, but in principle they are all pretty much the same except for some minor content variations. They are divided into traditional solders and plumb solders. In this paper I will explain the different types of solders, discuss the proper solder for the application, be it sizing, fabrication or assembly. We cover safety and eye protection. Solders used in the US and abroad are discussed. Detailed information when to solder, when to weld, soldering picks, soldering techniques, torch use, fuels, flames will be addressed. The use of video clips makes this paper lively, interesting and educational.

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Flameless Tunnel Technology: a fast, safe and ecological method of producing gold and silver ingots

Can safety and respect for the environment co-exist in a new method for producing bank ingots? Why is it important to transform minerals extracted from mines or retrieved metals into ingots as quickly as possible? The traditional method is called the “melting-pouring process” and consists of top-pouring molten metal from the crucible to the mould and the use of flames to protect the surface of the product with the consequent problems of energy dispersion, safety risks and an unhealthy environment. The method that now runs parallel with the “melting pouring process” is the natural evolution of a project called “Flameless Tunnel Technology” that began 15 years ago in IECO and refers to an ingot production system using a tunnel oven in a protected atmosphere. This new process eliminates the problems of the traditional system, increases safety conditions and produces perfect surfaces on the finished products without free flames or smoke. The process will be described and the advantages and disadvantages of the two methods will be analysed during the presentation, highlighting the strong and weak points of both systems.

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The new nano composite ceramic e-coatings-Comparative study of abrasion and tarnishing resistance.

Ceramic nano – composite cataphoretic coating (e – coating) is an innovative product ideal for the protection of metal surfaces. Thanks to the presence of ceramic nano-particles in its formula, its wear resistance is improved as well as its feeling sensation to the touch with respect to the traditional e-coatings available on the market today. Moreover, as it is colorable by the addition of pigments, it offers the possibility to combine either protective and decorative purposes on jewelry components. This paper is focused on presenting both transparent and several colored e-coatings aside experimental results confirming their exceptional resistance to wear and tarnish in comparison with traditional coatings obtained by chemical passivation, electroplating and PVD technique.

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Dynamic re-crystallization and the hot working of precious metals

Although the process of hot working metal dates back to the mists of time, it has only been sufficiently understood in the last 40 years. The greater workability of metals and alloys at high temperature is due to the quick change in microstructure of which dynamic re-crystallization is one of the main aspects. Probably due to the ease with which precious metals can be cold worked at room temperature, it is hard to find information on hot working. However, the difference in results between cold working followed by annealing and hot working is interesting and useful to know in order to improve product quality. This work aims at giving a general and simplified description of the micro-structural phenomena, like dynamic recovery and dynamic re-crystallisation, that occur during hot working. The advantages of hot working on some precious metals alloys will be illustrated by means of practical examples that will include an analysis of the microstructures.

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Computer Simulation in Jewellery Technology : meaningful use and limitations

In the past, materials have exclusively been developed by empirical correlation of chemical composition, manufacturing processes, and obtained properties. This processing, based mainly on guesswork and good luck, in the age of increasing experimental costs has been overshadowed by rapidly developing computational materials design. In many industries modern simulations tools are successfully applied for the improvement of materials and processes, while in jewellery technology their potential is only used to a limited extent. This paper describes different simulation methods and shows how these could be applied in jewellery technology in a meaningful way. Thermodynamic simulations allow the calculation of phase diagrams, which are required for alloy design, heat treatment processes and to understand segregation phenomena. In contrast to binary and ternary diagrams from handbooks the simulation allows dealing with real multicomponent alloys. Examples from higher order gold alloys will illustrate the possibilities. Computational fluid dynamics can be used to describe the complex flow of the melt during casting and the temperature distribution as a function of time. However, rather than providing exact solutions up to the last process parameter, the CFD simulation can be seen as a tool for the improvement of casting quality, in order to establish helpful guidelines. Examples from static and centrifugal investment casting will show the possibilities and limits of the simulation. In the outlook the potential and requirements for further use of simulation techniques in jewellery technology (e.g. precipitation hardening, continuous casting, microgranulation) will be discussed.

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