Carat (purity)

Engraving on the backside of a watch, showing that it contains 14 carat.

The carat is a unit of measurement for gold alloys. In that context, one carat gold means that the twenty-fourth part of an alloy is gold, the other parts are made of other metals, generally silver or copper. Pure gold would be soft, which makes it unusable for many purposes. Alloyed gold is harder than pure gold and so more suitable for applications such as jewellery. An alloy that has 24 carat actually contains 99.9 percent gold, 18 carat gold contains 75 percent gold . Sometimes, a scale up to 1000 is used; as an example, gold 585 mean there is 58.5 percent gold in the alloy. This means that "Gold 585" actually contains 14 carat.

Carat (purity) Media

1 troy ounce of four nines fine gold (999.9)
A 2019 American Silver Eagle bullion coin with a fineness of 999 (three nines fine), together with a Walking Liberty half dollar with a fineness of 900 (one nine fine); this latter alloy is also often referred to as 90% silver or coin silver.
Carob (Ceratonia siliqua) pod and seeds, origin of karat via Arabic qīrāṭ which itself comes from the Greek word for the seed kerátion

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