In Turkey, the term 'ayar' is used to indicate the purify level of gold, internationally known as "carat". As you know that, carat is a unit to be used to measure of diamond and other precious stones' weights. 1 carat is equal to 0,2 gram, i.e. 200 milligrams.
Using of the weight unit carat as a rate indicates purify level of gold dates back to very old times. The weight of pure gold coins used by Germen named Mark is 4,8 gram. 4,8 gram is equal to 24 carats. Therefore, it's began to be called pure gold as 24 carats. Later, for purify levels of these coins, that had decreased purify levels by other materials such as copper, specific rates were determined according to pure gold amount in alloy and these rates were expressed as carats.
To explain in more detail:
- 1 gram=1000 milligrams (mil).
- The 24 ayar gold is the pure gold and therefore the gold proportion is 0, and so 1 gram has 1000 milligrams of gold.
- In 22 ayar gold, 22/24 of the alloy is gold. This means approximately 91% is gold. So, 1 gram has 916 milligrams of gold.
- In 18 ayar gold, 14/24 of the alloy is gold. This means approximately 75% is gold. So, 1 gram has 750 milligrams of gold.
- In 14 ayar gold, 14/24 of the alloy is gold. This means approximately 58% is gold. So, 1 gram has 583 milligrams of gold.
- In 8 ayar gold, 8/24 of the alloy is gold. This means approximately 33% is gold. So, 1 gram has 333 milligrams of gold.
The pure gold is a very soft element, so it's mixed with copper in order to increase its hardness. A cause of mixing gold with other elements is to achieve different colors. The natural color of gold is yellow. Gold has colors according to the elements used in the alloy such as silver, copper, palladium.
For example, let's address an 18 Ayar gold alloy consists of elements other than gold by 25%:
Alloys consist of,
- 25% (all) silver form green gold,
- 5% silver and 5% copper form yellow gold,
- 9% silver and copper form pink gold,
- 4,5% silver and 20,5% copper form red gold,
- 9,9% silver, 5,1% copper and 6,4% palladium form white gold.