Picture credit, cc license: wikipedia user Catton
Karat (North-American writing) or Carat (British writing) is a measure for the fineness of gold, mostly used for gold jewelry. It should not be confused with the the diamond weight of karat, which corresponds to 2 gram. The scale of the “gold karat” has a maximum of 24, which is also called fine gold.
Karat is abbreviated as Kt or C. The roots of the English word karat/carat can be found in the Arabic qīrāṭ (قيراط). It entered the Greek as kerátion (κεράτιον). The Romans adopted it as carratus. The French changed it to le carat, where it then entered the English language as a loanword.
The gold content of an alloy (metal-mix), is based on a 24-scale. Thus, 1-karat gold contains 1/24 gold (4,2%) and 23/24 other metals. (The content of gold and other metals refers to its weight.) 24-karat gold has theoretically a gold content of 24/24 part, i.e. 100%. However, it is impossible to refine 100% pure gold. Therefore, a gold content of 99.9% is considered as 24 karat.
Common karat values are:
- 24 karat, fine gold, at least 99.9% gold content
- 21,6 karat, coin cold, 90.0% fineness
- 18 karat, 75.5% fineness
- 14 karat, 58.5% fineness
- 9 karat, 37.5% fineness
- 8 karat, 33.3% fineness
Popular caratage values, based on country:
- Arabic countries, Far East: 24 karat
- Arabic countries, Indian Subcontinent: 22 karat
- Arabic countries, in the Gulf Region: 21 karat, 18 karat
- Southern Europe, Portugal: 19.2 karat
- Southern Europe, Mediterranean: 18 karat
- Russia: 9 – 14 karat
- UK: 9 – 22 karat
- 10 – 18 karat
To calculate the value of gold jewelry, one has to first determine its caratage (usually written on the jewelry). The calculation is purely based on the gold content, as other metals have a far inferior value and are therefore negligible (except for precious stones).
The picture shows a jeweled Indian gold ring.