carat
Americannoun
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a unit of weight in gemstones, 200 milligrams (about 3 grains of troy or avoirdupois weight). c., ct.
noun
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a measure of the weight of precious stones, esp diamonds. It was formerly defined as 3.17 grains, but the international carat is now standardized as 0.20 grams
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Usual US spelling: karat. a measure of the proportion of gold in an alloy, expressed as the number of parts of gold in 24 parts of the alloy
Etymology
Origin of carat
1545–55; < Medieval Latin carratus (used by alchemists) < Arabic qīrāṭ weight of 4 grains < Greek kerátion carob bean, weight of 3.333 grains, literally, little horn, equivalent to kerat- (stem of kéras ) horn + -ion diminutive suffix
Explanation
Precious jewels are measured in carats instead of ounces or grams. If your sister gets a three-carat diamond ring, she's getting a ring that weighs 600mg, which is big enough to be called "a rock." A variant of carat is karat. The former is usually used with diamonds and is a measure of weight, whereas the latter is usually used for gold and is a measure of purity. One karat is 1/24th of the mass, so 24-karat gold is pure. An 18-karat gold ring is 18/24 (or 3/4) gold and 6/24 (or 1/4) other metals.
Vocabulary lists containing carat
In A Sedimental Mood: Rock and Gem Vocabulary
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The White Album
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Little Richard (1932–2020): Tribute List
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"To find something in five carat of this quality and this colour is truly remarkable."
From Barron's • May 13, 2026
It’s not something I had even considered while I was worrying about the cut, carat, clarity and color.
From MarketWatch • Feb. 3, 2026
A harbinger of disaster is a replica of the harness-like 2,842 carat necklace from the “Diamond Necklace Affair” of 1785.
From The Wall Street Journal • Jan. 8, 2026
The internet hummed with commentary, memes, and close analysis of carat weight.
From Salon • Aug. 31, 2025
“A ton. Small unmarked ingots. Twenty-four carat only. Well, at least it’s a nice round weight.”
From "Artemis Fowl" by Eoin Colfer
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
