Used in a very pure form, Platinum’s wear and tarnish resistance characteristics make this almost white metal particularly suited to ﬁ ne jewellery. While Platinum’s popularity is higher than ever, its value changes in line with its availability, but is normally around 200% the value of Gold. Platinum and 18ct Gold are both malleable metals and will dent if hit on surfaces harder than themselves. Settings may become loose if knocked. Stones do not come loose unless knocked.
is the softest and most malleable of the precious metal family. As a pure metal, it is too soft for most jewellery applications and must be alloyed with other metals to give it strength and durability. Fine Gold is also a very rich yellow, therefore to colour the Gold, it has to become an alloy. That is to say, the 24 carat, 100%, Gold has other metals added to make it 18ct or 9ct coloured Gold. 18ct Yellow Gold can be made from 75% Pure Gold with 12.5% Silver and 12.5% Copper. 9ct Yellow Gold may have 37.5% Gold, 15% Silver and 47.5% Copper.
The Gold Myth
In Australia, there is a choice between 9,14 and 18 carat (ct) gold. It is a common misconception that 9ct gold is harder wearing than 14 or 18ct gold. 9ct has a Vickers hardness of 120 and 18ct has a Vickers hardness of 125. While this shows that 18ct is harder, in practical terms 9ct and 18ct are much the same. 9ct is however, more difficult to bend and is a little springier than 18ct. Therefore a thin 9ct ring may be less likely to bend out of shape than a thin 18ct ring. However, if your jewellery is of good sturdy construction, neither metal will be likely to bend out of shape. The gold content in 9ct gold is very little, it has more parts copper and silver than actual gold. But, it is not so much about the proportion of gold but the types of metal it has been alloyed with that dictates how hard wearing the item of jewellery will be. It is, in fact, more likely that 18ct gold will be harder wearing than 9ct. Because using 9ct is often mixed with softer inexpensive metals, whereas 18ct gold is often alloyed with more expensive and harder wearing metals; 9ct uses less expensive alloys to help maintain the price structure between 9 and 18ct gold. You could; of course, mix 9ct gold with hard wearing metals but the added costs would be closer to that of 18ct gold.
To produce White Gold, a combination from either Silver, Platinum, Palladium or Zinc will be added. White gold jewellery may be cared for in the same way as yellow gold. As most white gold products have been rhodium plated, it is important to note that rhodium plating is not permanent. Rhodium plating will fade or wear over time. As it wears, the original colour of the metal beneath will show through. The length of time rhodium plating will last on a piece of jewellery depends on the individual wearer. Some people may find that the plating wears quite rapidly, while others will find that the colour lasts for a long period. In order to maintain the bright white colour, jewellery may be re-rhodium plated by a jeweller, as often as desired.
For Pink Gold, Copper will be added to the mix of Gold and white metals. Rose gold has a higher copper content than yellow gold, giving it a rose-reddish colour.
is actually an alloy of Silver, containing 92.5% Pure Silver and 7.5% other metals, normally Copper. Fine Silver (99.9% pure) is generally too soft for making most jewellery items, and so it is alloyed with Copper to give it strength and durability. Like other white metals, Fine Silver is fairly resistant to tarnishing, however, when alloyed with other metals (normally Copper) it can react with Oxygen. Other white metals can be used in the alloy (at extra cost), which will improve resistance to tarnishing and preserve the metal’s whiteness. Silver is quite soft and not as durable as other metals, the advantage however, is the price, when compared to gold, platinum etc. Sterling Silver will tarnish, requiring regular cleaning. Some people may experience skin reactions to sterling silver.