Gold Rates
The carat (abbreviation ct or kt) is a measure of the purity of gold alloys, 24 carat being pure gold. In the United States and Canada, the spelling karat (abbreviation k or kt) is used.
Therefore 24-carat gold is fine (99.9% Au w/w), 18-carat gold is 75% gold, 12-carat gold is 50% gold, and so forth.
Historically, in England the carat was divisible into four grains, and the grain was divisible into four quarts. For example, a gold alloy of 
fineness (that is, 99.2% purity) could have been described as being 23-carat, 3-grain, 1-quart gold.
The carat system is increasingly being complemented or superseded by the millesimal fineness system in which the purity of precious metals is denoted by parts per thousand of pure metal in the alloy.
The most common carats used for gold in bullion, jewelry making and by goldsmiths are:
- 24 carat (millesimal fineness 999 or higher)
- 22 carat (millesimal fineness 916)
- 21 carat (millesimal fineness 875)
- 20 carat (millesimal fineness 833)
- 18 carat (millesimal fineness 750)
- 15 carat (millesimal fineness 625)
- 14 carat (millesimal fineness 585)
- 10 carat (millesimal fineness 417)
- 9 carat (millesimal fineness 375)
- 8 carat (millesimal fineness 333)
- 1 carat (millesimal fineness 042)
Derivation
The word carat is derived from the Greek kerátion (κεράτιoν), “fruit of the carob”, via Arabic qīrāṭ (قيراط) and Italian carato. Carob seeds were used as weights on precision scales because of their reputation for having a uniform weight. (However, a 2006 study by Lindsay Turnbull and others found this not to be the case – carob seeds have as much variation in their weights as other seeds.) This was not the only reason. It is said that in order to keep regional buyers and sellers of gold honest, a potential customer could retrieve their own carob seeds on their way to the market, to check the tolerances of the seeds used by the merchant. If this precaution was not taken, the potential customer would be at the mercy of “2 sets of carob seeds”. One set of “heavier” carob seeds would be used when buying from a customer (making the seller’s gold appear to be less). Another, lighter set of carob seeds would be used when the merchant wanted to sell to a customer.
In the distant past, different countries each had their own carat, roughly equivalent to a carob seed. In the mid-16th century, the Karat was adopted as a measure of gold purity, roughly equivalent to the Roman siliqua (
of a golden solidus of Constantine I). As a measure of diamond weight, from 1575, the Greek measure was the equivalent of the Roman siliqua, which was 
of a golden solidus of Constantine; but was likely never used to measure the weight for gold.
Terminology
22/22K – a quality mark indicating the purity of gold most popularly used in India. This purity was adapted and practiced by the big jewelers and was later passed to jewel smiths. The first 22 signifies the “Skin purity”, the purity of the top layer of the gold jewelry, and the second 22 signifies that after melting purity of the gold jewellery will be 22-carat, or 91.67% of pure gold. This system is used to show consistency in the quality of the gold.
This practice was pioneered and introduced in the early mid-1980s by Nemichand Bamalwa & Sons of Kolkata, India, sparking a revolution in India as it forced jewelers to indicate correctly the after-melting purity, and heightened consumer awareness made it a most sought-after stamp or quality mark.
This symbol or stamp can be found in Asian countries like India, Sri Lanka, Pakistan, Bangladesh, Nepal, Yemen, and Persian Gulf countries.
