Translation guide
The unit of weight for gemstones and pearls, equal to 200 milligrams.
How many carats is this diamond?
Expressing the weight of a gemstone or pearl in carats.
The standard loanword for 'carat' used in jewelry contexts. It is the most common and natural way to express this concept in Japanese.
In English, 'carat' (gem weight) and 'karat' (gold purity) are distinct. In Japanese, both are expressed as カラット, but context usually makes the meaning clear. For gold purity, you may also see 'K' used (e.g., 18K).
18-karat gold
このダイヤモンドは2カラットです。
This diamond is 2 carats.