When you see fine antique jewellery made of a white precious metal, you are normally going to be looking at either silver, white gold or platinum. Some less expensive antique jewellery will be set in silver coloured metal which is non-precious metal, but I am concentrating on precious metals in this post.
Silver has been used for jewellery for thousands of years. It is malleable, soft and white and relatively easy to use. Its only drawback is its tendency to tarnish. Making objects out of silver is a long tradition, controlled by silversmiths. Silver hallmarks exist in many countries, with the UK and French hallmarks dating back to the 1300s. These hallmarks indicate the silver composition in the metal used. In the UK, the standard for silver is .925 of 1000 per cent silver which denotes sterling silver. In Austria, the standard is .895, Danish silver is marked .830, and Russian is marked 84, for .840. Some countries’ marks range from .800 to 970. In the US, early silver was stamped .900, but the standard now is .925
Platinum (meaning “little silver”) is a rare metallic element that is more expensive than gold. It is strong, doesn’t corrode or tarnish but is not easy to use because it melts at extremely high temperatures. There is evidence to show it was used in Egyptian, Pre-Columbian and Inca jewellery. The Spanish came across it in South American and discarded it. Generally, platinum needs to be combined with other metals such as copper, rhodium or iridium to create a workable alloy. In the 17th and 18th centuries, scientists in Europe, particularly in Spain and France attempted and, in many cases succeeded, to find processes through which platinum could be used. The Napoleonic Wars stopped progress but in 1803, a British scientist discovered a process to make a malleable alloy which could become mainstream. However, it was not until the mid 19th century that it began to be used in Victorian jewellery, as furnace heating temperatures increased. Jewellers like Fabegé and Cartier began to use it for high end diamond jewellery.
WWI saw restrictions being placed on the use of platinum in jewellery as it was needed to mark armaments. Its use flourished between the wars but in 1942, the Allies banned its use except for war purposes. Platinum has a legal hallmark in the UK and is usually an alloy comprising 95% platinum.
White gold: The restrictions imposed on the use of platinum by the various wars meant that a substitute for platinum was needed. An alloy of gold, palladium, and nickel was invented in 1913 and the patent was granted on December 28, 1915, to Karl Richter of Pforzheim. However, WWI stopped work on it. David Belais, an American manufacturer, patented ‘white gold’ in 1918, using an alloy of gold, zinc and nickel, but his patent was successfully struck down in 1926 due to lack of invention and prior art.
Because a white gold alloy using nickel could sometimes lead to skin irritation to wearers, palladium began to be used with gold to make white gold, however, it is very expensive and made the white gold produced a very costly item. The right mix of metals is still being sought. One patent lodged in 2005 used copper, silver, zinc and manganese.
One solution to the skin problems that can be associated with white gold made with nickel was the use of rhodium, a strong white coloured metal. Rhodium is electroplated over white gold but it needs to be replaced every few years.