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What is Carat?

Carat (also “karat” or “carat weight”) refers to the unit measurement of the purity and mass of gold alloys and gemstones. For gold, it measures the parts per 24, with 24 carats representing 100% pure gold.

Gold Carat Measurement

Pure 24 carat gold is extremely soft. Adding other metals creates gold alloys indicated by lower carat values - 18 carat gold is 18/24 or 75% pure gold. Common jewellery gold purity levels are 18 carat, 14 carat and 9 carat. The carat number stamped on gold jewellery signifies the purity.

Gemstone Carat Weight

For gemstones, a carat is a weight equal to 200 milligrams or 0.2 grams. Gemstone weight increases in carat increments - a 2 carat diamond is twice as heavy as a 1 carat. Carat weight helps determine gemstone value and pricing.

Carat (also “karat” or “carat weight”) refers to the unit measurement of the purity and mass of gold alloys and gemstones.

Origin of Term

“Carat” comes from the carob seed historically used to counterbalance scales. Its consistent mass made it useful for weighing gemstones and measuring gold purity.

Carat vs. Karat

In American English, the spelling “karat” is often used specifically for gold purity, while “carat” refers to gemstone weight. But in British English, “carat” can denote both. The words have the same meaning.

Importance

The consistent, standardized units that carat and karat provide enable jewellers and consumers to reliably gauge and communicate the quality of precious metal and gems based on certified weight and purity markings.

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