All about gold (and platinum)
Throughout history, gold has been treasured for its natural beauty and radiance. For this reason, many cultures have imagined gold to represent the sun.
Yellow gold jewellery is still the most popular colour, but today gold is available in a diverse palette. The process of alloying—mixing other metals with pure 24 carat gold—gives malleable gold more durability, but can also be used to change its colour.
White gold is created through alloying pure gold with white metals such as palladium or silver. In addition it is usually plated with rhodium to create a harder surface with a brighter shine. White gold has become the overwhelming choice for wedding bands in the US.
The inclusion of copper results in the soft pink complexion of rose gold while the more unusual colours such as blue and purple can be obtained from the addition of patinas or oxides on the alloy surface. Black gold for example derives its colour from cobalt oxide.
The weight of gold is measured in troy ounces (1 troy ounce = 31.1034768 grams), however its purity is measured in ‘carats’.
‘Caratage’ is the measurement of purity of gold alloyed with other metals. 24 carat is pure gold with no other metals. Lower caratages contain less gold; 18 carat gold contains 75 per cent gold and 25 per cent other metals, often copper or silver.
Fineness is another way of expressing the precious metal content of gold jewellery, and represents the purity in parts per thousand. When stamped on jewellery, usually this is stated without the decimal point.
All our jewels are made in 18kt gold.
18kt yellow gold is composed of 75% of gold (Au), 15% of silver (Ag) and 10% of copper (Cu).
18kt white gold is composed of 75% of gold (Au) and 25% of palladium (Pd) or platinum (Pt).
18kt rose gold is composed of 75% of gold (Au), 9.2% of silver (Ag) and 22.2% of copper (Cu).
Platinum might also be an alternative to white gold, but is more expensive because of its greater density and rarity.
Pure platinum is too soft to be used in jewellery, and is therefore often mixed with a small quantity of other metals such as rhodium, copper, or cobalt to make it hard enough to be used in jewellery.
The purity of platinum is measured in 1000 parts. When we use platinum in jewellery, it is generally with 950 parts of platinum and 50 parts of other metals.
Platinum jewellery are therefore purer than 18kt gold jewellery (with 750 parts of gold and 250 of other metal) as they contain a greater percentage of the precious metal.