English Reference

Word

carat

US/ˈkɛɹət/

UK/kˈæɹæt/

Definitions

01weight of gemstones

C1

n. a unit of weight for diamonds and other precious stones. One carat is equal to 200 milligrams.

n. a metric unit of mass equal to 200 mg, used internationally for weighing precious stones and pearls.

“She bought a beautiful ring with a one-carat diamond in the center.”

“The auction house estimated that the rare blue diamond weighed over fifteen carats, making it one of the largest of its kind.”

Technical

Usage

Often used as a compound adjective before a noun, such as 'a five-carat stone'.

Pitfall

The ring has a two-carats diamond.

The ring has a two-carat diamond.

When used as an adjective before a noun, 'carat' stays in the singular form.

02purity of gold

C1

n. a measure of how pure gold is, based on a scale of 24 parts.

n. a unit of proportion used to measure the fineness of gold, where 24-carat gold is pure.

“Pure gold is 24 carats, but it is usually too soft for most jewelry.”

“To increase the durability of the wedding band, the jeweler recommended using 18-carat gold rather than the softer 22-carat alloy.”

Technical

Teaching tip

In American English, 'karat' (with a K) is the standard spelling for gold purity, while 'carat' (with a C) is used for gemstone weight. British English often uses 'carat' for both.

Synonyms

karat

Real-World Examples

“Thieves later made off with the 18-carat loo when it went on display at Blenheim Palace, Winston Churchill’s Oxfordshire birthplace.”
The Guardian · 3 Sept 2026

Etymology

From Middle French carat, from Italian carato, from Arabic قِيرَاط (qīrāṭ, “carat, similarly small units such as inches”), from Ancient Greek κεράτιον (kerátion, “hornlet, carob seed”), from κέρας (kéras, “horn”) + -ιον (-ion, diminutive suffix). Doublet of quilate and keratin.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry

Level
C1 · Advanced
Frequency
Occasional
Updated

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