Our guide to precious metals and hallmarking
Hallmarking dates back to the 1300s when Edward I of England passed a law requiring any item made of silver, which was offered for sale, to be at least of equal quality as that of the coin of the realm (silver currency). The wardens of The Goldsmiths’ Company were tasked with visiting workshops in the City of London to assay (test) silver articles. If these articles were found to be below standard they were originally destroyed and the metal forfeited to the King. If they passed, each article received the King’s mark of authentication.
As pure gold is a relatively soft metal it has to be alloyed with base metals to increase its strength and durability when making jewellery. These alloys include silver, copper or palladium amongst others. The ratio of gold to these other metals is measured in 24 parts. These are called 'carats', 24 carat gold being pure gold; therefore 18 carat gold is 18 parts pure gold and 6 parts alloyed metals. 9 carat gold is 9 parts pure gold and 15 parts other alloyed metal. We still use the carat system when describing gold i.e.; 9ct, 14ct, 18ct, however where hallmarks are concerned we now measure gold by the millesimal fineness system in which the purity of gold and other precious metals is now measured by parts per thousand and this is how they are now shown on modern hallmarks. The most popular carat weights in today’s jewellery are 18ct (fineness 750) and 9ct (fineness 375) this shows us that 18ct is 750 parts pure gold compared to 250 parts alloys and 9ct is 375 parts pure gold to 625 parts alloys.
Some countries use the word Karat instead of Carat to distinguish it from the weight of gemstones. As we spell them the same it is important not to confuse the two.
The colour of the gold can be changed depending which alloys you infuse with the pure gold, for instance rose gold is obtained by alloying more copper with gold giving it a reddish colour.To obtain white gold, the pure (yellow) gold is alloyed with palladium, zinc and silver to name a few. The result however is still that of a slight yellow colour, so to give white gold its brilliance and shine it is coated with rhodium which is extremely hard and acts as a whitener. This is common practice with all white gold. As the rhodium is a coating it will need to be re rhodium plated from time to time depending on the conditions of wear.
Silver is a very ductile, malleable (slightly harder than gold in its purest form), with a brilliant white metallic lustre that can take a high degree of polish. This makes it a great metal for jewellery making.
Silver has always been less expensive than this is because silver is found more readily than other metals and is in fact a by-
Like gold, silver isn’t used in its natural state. It is alloyed with other metals to make it more suitable to work with.
The most common fineness of silver here is 925. Which means 92.5% silver. This level of fineness is known as Sterling Silver.
Platinum is pure, naturally white and is kind to the skin. Platinum is a naturally white metal so it will not cast any of its own colour into a diamond. Usually 95% pure (by comparison 18 karat gold is 75% pure), platinum never fades or tarnishes but keeps its natural white colour for a lifetime. As platinum is so pure, it is naturally hypoallergenic and ideal for those with sensitive skin.
Platinum is eternal, with everlasting radiance and durability. Platinum’s unequalled durability and resistance to wear makes it the most secure and protective metal, which means your jewellery will be protected for a lifetime of wear. Platinum does not change shape or wear away so precious stones are held firmly and securely. The density of platinum makes it more durable than other jewellery metals.
Platinum is rare, a treasure coveted by influential individuals for centuries. Found in very few places around the world, platinum is 30 times more rare than gold. Platinum jewellery is exclusive, a statement of individuality, and desired by those in the know.
Palladium is a member of the Platinum group of metals with many similarities to Platinum. It does not tarnish or lose its whiteness and does not need rhodium plating. It is rarer than Silver and Gold and is hypoallergenic due to its high purity with minimal alloying. As with platinum, palladium wears well and any surface scratches can be easily polished away.
Palladium is generally worked at a purity of 95% pure, and is comparable in weight to 14ct gold. Hallmarking on Palladium became obligatory on January 1 2010.
WHAT IS A HALLMARK
A complete hallmark consists of three compulsory punch marks:
The Goldsmiths' Company Assay Office also applies two optional marks, at no extra cost:
Click the hallmarking chart to view >>>
Quality Jewellery in Canterbury
Anthony W Pearce
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