All that glitters...

The Birmingham Assay Office has been protecting traders and customers for over 230 years and it is still as vital today. Whatever the questions posed in precious metal and non precious metal testing – The laboratory at The Birmingham Assay Office has the answers

THE Laboratory at The Birmingham Assay Office has been inundated with requests for advice and additional testing following the recent national press coverage with regard to unsafe levels of lead being found in some items of children’s jewellery and toys. The laboratory under the guidance of technical director Mr Dippal Manchanda undertook the testing.

The laboratory at The Birmingham Assay Office is also the leading Nickel testing specialist in the UK and is the only UKAS accredited Laboratory to offer the unique quick nickel test.

The nickel legislation addresses a serious problem. A growing number of people are becoming Nickel sensitive and suffering life long problems as a result. It is estimated that between 10% and 15% of women and 2-5% of men in Europe are nickel sensitised. Nickel sensitisation usually occurs as a result of nickel being released from an item inserted through a body piercing and entering the body. Nickel and Nickel salts can be dissolved by sweat and then penetrate the skin, interacting with the immune system to induce nickel allergy which then remains with the sufferer for life.
The purpose of the Nickel regulations is twofold - to prevent people becoming sensitised to nickel and to reduce the risk of prolonged and direct contact with articles with a high level of nickel release which could trigger an allergic reaction. The legislation aims to reduce the danger of a customer suffering bad reactions from a non-conforming product. It applies to all items which are intended to come into prolonged and direct contact with the skin for example: necklaces, bracelets, chains, anklets and finger rings, wristwatch cases, watch straps, rivet buttons, rivets, zippers and earrings.
The testing of all post assemblies intended for use in any sort of body piercing is therefore very important. Since September 2005, the regulations have required post assemblies to comply to a more rigorous level of nickel release than other items.
In response to customer demand the laboratory has developed a “Quick Nickel” test which accurately identifies items which would definitely pass BS EN 1811 and comply with the UK Nickel regulations. The test is UKAS accredited, inexpensive and can be completed within three days. The Laboratory also carries out Nickel release testing according to procedures based on BS EN 1811:1999 and BS EN 12472.

The Birmingham Assay Office has a long established reputation within the jewellery trade as an independent centre of quality assessment and expert opinion for precious metals and gemstones.
The testing and analysis of precious and non precious metals has been fundamental to business since it was founded by Act of Parliament over 230 years ago. The Laboratory at The Birmingham Assay Office is accredited by UKAS to ISO 17025 standard and follows rigorous quality assurance and quality control practices. It is widely acknowledged for its expertise and its extensive range of specialist testing and analysis procedures.
The services provided by the laboratory are not only appropriate to the Jewellery trade - they are also applicable to any potential customer who requires a compositional test whether the sample is metal, liquid or a powder.
The laboratory is one of the UK’s leading test houses for precious metal analysis and nickel compliance. Tens of thousands of watches and pieces of jewellery, both precious and costume, are tested here every year to make sure they comply with the European regulations for Nickel release. The Laboratory also carries out precious metal analysis for all sectors involved in manufacturing and selling precious metals on a daily basis and can test for lead and compliance to the ROHS Directive.

Many consumer products include precious metals and the laboratory is frequently called upon to investigate and carry out metal analysis and quality checks on items of jewellery and watches and on items plated with precious metal.

The amount of precious metal contained in an alloy makes a significant difference to the value of the item. Even an expert could be the victim of a misleading description as it is impossible to determine the composition of a metal alloy simply by looking at it (unless the item is hallmarked, then the precious metal content can be calculated). There are various test methods to determine the precious metal content of jewellery articles and both destructive and non-destructive methods can be used. Experts in the laboratory will select the most appropriate option and then use their expertise and experience to provide the results.

Examples of the tests carried out include:

Touch Acid Screening - A basic chemical screening test used to detect plating, sub-standard parts or excessive use of solder. Small amounts of reagents are applied directly to the article, and the colour change which results indicates the fineness of the metal. If an accurate analysis is required, fire assay, potentiometric titration or ICP-OES is used.

XRF Analysis - X-ray fluorescence analysis gives rapid results of the precious metal and non precious metal content of a range of products. It can also be used for plating thickness determination and has the great advantage of largely being non-destructive, unlike other methods which result in damage to the surface finish of the product.
Depending on the thickness of plating a more detailed destructive examination can be undertaken. It involves taking a cross section of the article, mounting it in resin, polishing and examination of the coating(s) using an optical microscope. Results can be recorded photographically.

Assaying - Where a highly accurate result is required, the most accurate results are gained by scraping a small sample of metal from the article and carrying out an assay. The method used will depend upon the metal present.

Tarnishing - Silver has an inherent problem with tarnishing which can lead to consumer dissatisfaction. The laboratory has developed unique tests to assess whether an item is susceptible to tarnishing or not. This can sometimes be a result of poor quality plating practices.

ROHS - The Restriction of Hazardous Substances in Electrical and Electronic Equipment Directive applies to all those who manufacture, sell, distribute or recycle electrical and electronic equipment. RoHS in conjunction with Waste Electrical and Electronic Equipment (WEEE) legislation aims to protect human health and the environment by restricting the use of certain hazardous substances in new electronic and electrical equipment. RoHS imposes the removal of lead (including leaded solder), mercury, hexavalent chromium, cadmium and two flame retardants from new electrical equipment sold after 1st July 2006. The Laboratory can test the lead, mercury, chrome VI, cadmium and flame retardant content of articles to confirm that they comply to RoHS.
Lead testing - In addition to testing items under the requirements of RoHS the laboratory also carries out analysis on lead content and lead migration of leachable lead, especially in relation to toys, childrens jewellery, and watches, in line with requirements of the many different UK, EU, USA and Canadian standards, laws and guidelines.

The laboratory offers its customers two options - the first is testing by ICP- OES to establish lead content by weight. In this case USA legislation defines a safe limit of 0.06% (600ppm) lead. This test is particularly appropriate for checking a product which has been specified as “lead free” to ensure that there are only trace levels of lead present. 
Alternatively products may be tested for release of lead. In Europe the closest parallel legislation is the Toy Safety Regulations which require items to be tested by BS EN 71-3 to establish the level of migration of lead and other dangerous elements from toys. This is intended to ensure that articles which may be sucked or chewed by a child are safe and the permitted level is defined as less than 90 mg/Kg (equivalent to 0.009%, or 90ppm) leach able lead. 
White gold has risen in popularity over the past few years and so have the number of queries from consumers and jewellers as to what exactly can be called “white”. There is currently no established or recognised means of defining either the composition of white gold, or the colour it should be.
It is widely acknowledged that there are huge variations in the colour of white gold on sale and also in the expectations of the consumer. White Gold is available in 9ct, 14ct and 18ct and the alloy is usually bleached by the addition of silver, palladium or nickel, or a combination of all three. Predictably the result of these compositional differences is quite a significant variation in colour.

In response to the problem the laboratory launched an initiative to establish a recognised retail definition of white gold. From the consumers’ point of view it is the colour which matters most and the objective was to establish a standard to scientifically measure the colour value of the item.

Following in depth research, the Yellowness Index - ASTM D1925, which is widely used in the plastic and paint industry - was finally adopted. The more colour present the higher the yellow Index Vd. For example, rhodium is at about 6.4 and conventional yellow gold has a value of 35 or more. This index allowed an acceptable ‘order of whiteness’ to be established.
These standards have been adopted as a recognised code which will benefit the jewellery consumer worldwide.
The laboratory also holds courses at the Birmingham Assay Office under the supervision of Dippal Manchanda. The laboratory also carries out investigative work for bodies such as Trading Standards, and undertakes research projects for public and private enterprises.

Considerable ongoing investment in industry state of the art equipment coupled with the continuous professional development of all technical personnel will ensure that The Laboratory remains at the forefront of technology for many years to come.

By Dippal Manchanda. He is the Technical Director at the Birmingham Assay Office and oversees all work carried out at in The Laboratory.