Gold

Gold. Soft, heavy and with a deep, rich colour (in fact one of the few metals with colour at all) it has been coveted throughout history. In its pure form, though, its malleability makes it unsuitable for fine jewellery that will see much wear. For this reason, various alloys have been developed. The process of alloying – adding other metals to the gold – hardens and strengthens it and makes finer work possible. It also gives us the chance to influence the colour a bit. Think ‘white gold’ or ‘rose gold’.

In Australia we are most familiar with 18 carat and 9 carat gold. Strictly speaking these terms are outdated and have been replaced by the millesimal system but most jewellers use them out of convenience and habit. The following chart shows the most common carat values of gold alloys and their equivalent millesimal value:

18ct gold has proven to be the best in terms of colour, strength and workability and most high quality, handmade gold jewellery is made in 18ct. It is comprised of 75% pure gold mixed with 25% alloy and stamped ‘750’. In 18ct yellow gold the 25% alloy is a combination of copper and silver. Adding silver lightens the colour so copper helps bring it back. In 18ct rose gold the 25% alloy has proportionally more copper, which imparts the pinkish hue. 18ct white gold has silver and palladium in its alloy. Both are white metals which wash out the gold’s natural colour, but as there is only 25% alloy if it is to be 18ct some of the colour remains, leaving more of a warm grey then true white. For this reason white gold is often plated with rhodium, giving it a bright, white surface.