In the world of jewellery, precious metals include gold, silver and platinum. Each of these precious jewellery metals have unique properties and qualities, so read on and learn more.
Pure gold is too soft to use for jewellery – it would bend very easily when worn. Because of this, gold must be mixed (alloyed) with other metals that are harder. This decreases the purity and makes the alloyed metal practical for use in jewellery. Karat (abbreviated as ‘kt’) is a measure of the purity of gold.
Popular gold jewellery karats
24 kt – pure gold
22 kt – 91.6% gold
18 kt – 75% gold
14 kt – 58.3% gold
10 kt – 41.7% gold
The higher the karat, the purer the gold content. The sweet spot of purity, durability and beauty is less than 20 kt but more than 10 kt. Most gold jewellery is made in 14 or 18 kt.
Gold is unique in that, through alloying, you can create gold of different colours. The most commonly used in jewellery are yellow, white and rose.
Pure gold is already naturally yellow, but the ‘yellow gold’ used in jewellery (again, usually 14 or 18 kt) is created by alloying pure gold with metals like copper and zinc. Yellow gold is the most hypoallergenic and malleable (easiest to work with) of all the different gold colours.
Diamonds with lower colour grades can be set in yellow gold, offsetting the yellowish hues that are common in diamonds with lower colour.
To get white gold, the pure gold is alloyed with nickel, manganese or palladium and then plated with rhodium.
White gold is an affordable alternative to platinum, and is more durable and scratch-resistant than yellow gold.
For diamonds with a very high colour grade (colourless or near-colourless), setting them in a white metal will really accentuate the clearness of the stone. Setting diamonds with colour grades below J in white gold or platinum might negatively highlight any hints of yellowish hues in the diamond.
Rose gold is an alloy with copper. The more copper, the redder the gold becomes – leading to the various red, rose and pink gold offerings. A typical rose gold alloy will be 75% gold and 25% copper.
Copper is a very durable metal and helps to make rose gold a strong metal for use in jewellery. Rose gold is a great choice as it tends to complement all types of skin tones.
Platinum is a naturally white precious metal that is very durable and dense, making it a great choice for use in jewellery. It is very malleable, but has a very high melting point (which makes it a little more technically challenging to work with). Its name comes from platina, which is Spanish for ‘little silver.’
As it is so naturally durable, platinum does not have to be alloyed with a lot of other metals to make it durable enough for regular wear like gold does. It is used in jewellery at 95% purity, with the remaining 5% typically being palladium, iridium, ruthenium or other alloys.
Naturally white, stronger than gold, acid-resistant and hypoallergenic, platinum is an ideal metal for jewellery. It does not oxidize and doesn’t require rhodium plating like white gold.
Other precious metals in the platinum group include palladium, rhodium, ruthenium, osmium and iridium.
Like gold, pure silver is too soft for jewellery. Silver is usually alloyed with copper, a harder metal, to be used for jewellery. Sterling silver contains 92.5% silver, commonly referred to as ‘925’.
Other metals like germanium, zinc and platinum may be used instead of copper to give different properties to the alloyed silver.
Fine silver is 99.9% silver. This grade of silver is used to make bullion bars for trading and investment. Fine silver is too soft for most practical uses.
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