Home / Gemstones / Gemstones
12 December 2017
Gold is dense, soft and shiny and is the most malleable and ductile pure metal known. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. The purity of gold is expressed in carats (ct), not to be confused with the carat weight of gemstones.
Pure gold is 24ct, but this is too soft for everyday use in jewellery. As a result, gold is alloyed with other metals to make it more durable and wearable. The type of alloy used will also affect the colour of the gold.
The caratage of the jewellery will tell you what purity the gold is: 9ct gold is 37.5% pure (mixed with 62.5% alloy) 18ct gold is 75% pure (mixed with 25% alloy) 9ct and 18ct gold are the standard gold purities used in South African and European manufactured jewellery. United States manufactured jewellery tends to be available in 10ct (42% pure) and 14ct (58% pure) gold.
Yellow gold is alloyed with silver and copper and is the most frequently used type of gold there is. Considered more "traditional" than white gold, it is still favoured in certain parts of the world. Yellow gold is often used to set diamonds that are of a lower colour on the diamond colour scale, for example from colour K - Z, as the yellow colour of the gold can "disguise" the tinted colour of these diamonds.
White gold is simply pure (yellow) gold that has been alloyed with a large percentage of white metals, including platinum, palladium, nickel or zinc. Because it is impossible to turn a naturally yellow metal completely white, all white gold is electroplated with rhodium (a platinum group metal). Over time, this rhodium plating wears off, exposing the natural grey-ish white colour of white gold. This leads many consumers to believe that white gold "tarnishes". In fact, it is just the rhodium plating that has worn off and by re-rhodium plating the item of jewellery, the original splendour of the jewellery can be restored in a cost-effective manner.
The use of white gold predates the emergence of platinum and palladium into the jewellery market. White gold is ideal for enhancing the white colour and brilliance of diamonds in the D - K colour categories. White gold can be slightly more expensive than yellow gold, due to the fact that it is alloyed with some of the more expensive platinum group metals.
Rose gold is alloyed with copper and sometimes silver. The higher the copper content, the stronger the red coloration, as pure gold is yellow and pure copper is reddish. A common alloy for rose gold is 75% gold and 25% copper by mass.
Despite being alloyed for greater durability, gold jewellery should still be carefully looked after. Try to avoid wearing your jewellery when doing rough work or handling chemicals and always store jewellery items individually to prevent items from scratching each other. Katannuta diamonds can manufacture any jewellery item in 9ct or 18ct gold, and in yellow, white or rose gold. Please contact us directly for all your gold jewellery requirements.