Working for clients around the Globe
Precious Metals
Did you know ?Metallurgy is the science of the structure of metals and their suitability for particular functions.
While studying for his honours degree Alan studied metallurgy, and in particular the structures and properties of silver, gold, and platinum. Having the knowledge and understanding of this information is important when hand working the materials so that you can maximise the benefits of their durability, ductility, malleability, and reflect ability.
Below is some information about the four metals we use.
Platinum
Did you know ?
It has been reported that if all the platinum in the world was poured into an Olympic sized swimming pool it would barely come up to your ankles. Which when you think about it, is not a lot.
It was the South American indians of Columbia who were the first known peoples to use platinum some time before 1735. It was in this year that the Spaniard Antonio de Ulloa discovered the indians using the metal and sent it back to Europe. The name Platinum comes from the Spanish platina – little silver.
Platinum is recovered from a black ore that looks for all the world like coal. It require 2 tonnes of this ore to extract 1 ounce of platinum. Approximately 30 tons of platinum are mined every year around the world. It has a melting point of 1772 C., which is far higher than gold or silver, and is alloyed with most commonly copper, to produce the hallmarking standard of 950 - which means 950 parts per 1000 are platinum. The remaining 50 parts is normally copper to allow the platinum certain working and wearing properties, but also ruthenium and iridium are used.
Platinum is one of the most ductile metals known. Ductile meaning the ability to be drawn down into finer and finer wire, platinum can be drawn down to a wire that is half the thickness of a human hair. It is also a very dense metal - or if you like a heavy metal. In comparative terms it weighs approximately 1.35 times the weight of 18ct.gold and nearly twice the weight of sterling silver.
Platinum is by far the hardest of the precious metals we use so is ideal for use in stone settings and shanks of engagement rings and wedding bands.
Palladium
Did you know ?
Palladium was discovered by William Hyde Wollaston in 1803. He named the metal Palladium in 1804 after the asteroid Pallas, discovered two years earlier, and the Greek goddess of wisdom.
Approximately 24 tons of palladium are produced around the world annually. It has a melting point of 1552 C. which is a good bit higher than silver and gold but not as high as platinum.
Palladium has for some time been alloyed with gold to bleach it white and produce white gold, commonly used in the production of jewellery.
Until recently, and apart from a short period during World War 2 when platinum was declared a strategic government resource and palladium was used for jewellery bands, palladium’s use in jewellery has been confined to its use in producing white gold. In 2006 however some bullion dealers started producing palladium in forms suitable for jewellers. Since then it has become very popular and is seen as a very good substitute for white gold.
We are led to believe by the bullion companies that in 2006 we were the first jewellers in Scotland to hand make in palladium. The standard of alloy we use is 950 – 950 parts per 1000 palladium, the same standard as is the hallmarking standard of platinum.Gold
Did you know ?
Pure gold is one of the most malleable metals known - 1cm 3 - barely the size of a sugar cube can be beaten or rolled into thinner and thinner sheet that would spread more than 1 meter square. The sheet can be so thin as to be translucent.
Gold is 1 of only 2 metals occurring in nature that are coloured, the other being copper.
Every year approximately 1,400 tons of gold are mined around the world mainly in South Africa, USA, Canada, and Russia. It is estimated that 50% of the worlds supply of gold is stored in the United States Treasury Department’s gold depository Fort Knox Kentucky, considered to be the most secure building in the world.
Pure gold has a melting point of 1064 C and is very soft so other metals are added to it in varying quantities to make it harder and also alter its colour. The term used to describe the fineness of these alloys is CARATS. The hallmarking standards in Britain are 9ct. 14ct. 18ct. 22ct.
9ct. 9 parts per 24 gold or 375 parts per 1000
14ct 14 585
18ct 18 750
22ct 22 916
The metals that are added to make these changes are;
SILVER acts to harden gold in conjunction with copper. Silver also whitens its colour.
COPPER reddens gold and hardens it especially when added with silver.
ZINC Significantly lowers the melting point of gold alloys so is perfect to add when making solders. Zinc also acts as a secondary whitener.
PALLADIUM is a primary whitener of gold especially in 18ct. alloys. It also hardens gold and raises the melting point considerably. 1180 - 1235 C
Silver
Did you know ?
Silver is one of the most reflective metals known. It reflects colours more accurately than any other metal. It has an optical reflective ratio of 97%.
Because of its reflective properties and before the advent of digital technology, silver was exclusively used in photography, both on the film in your cameras and the papers used to print your enlargements. In the past the reflector plate of a good quality mirror was also made from silver.
Silver is also a very malleable material and this combined with its reflective properties makes it the perfect material from which to make large decorative objects such as tea and coffee pots, candelabras, and table centres.
Approximately 9950 tons of silver are mined each year around the world. Silver has a melting point of - 961 C - and is the softest of the three noble metals. It is therefore alloyed with copper to make it harder. The British minimum standard for a silver alloy is commonly known as ‘Sterling Silver’ or depicted by the numbers 925. This means there are 925 parts per 1000 silver and 75 parts copper.
Although silver requires the copper to harden it, the inclusion of the copper has been and is the scourge of many a silversmith over the centuries. The reason for this is that under heat, annealing and soldering, the copper through the alloy and just under the surface oxidizes. If this is left on the metal when polished it shows as a greyish-brownish stain. This is called fire stain. To get a good polish on any silver item all of this staining requires to be removed which causes in some cases a fare amount of work.
Many mass produced jewellery items are plated with a thin layer of fine silver to mask this discolouration which wears off over time.