Carat, or Carrat, the name of that weight which expresses the degree of fineness that gold is of.

The mint-master, or custom, have fixed the purity of gold at 24 carats; though it is not possible so to purify and refine that metal, but it will want still about one fourth part of a carat in absolute purity and perfection. The carat is divided into $\frac{1}{2}$, $\frac{1}{3}$, $\frac{1}{4}$, $\frac{1}{5}$, and $\frac{1}{6}$. These degrees serve to distinguish the greater or lesser quantity of alloy therein contained; for instance, gold of 22 carats, is that which has two parts of silver, or of any other metal, and 22 of fine gold.

Caract is also a certain weight which goldsmiths and jewelers use wherewith to weigh precious stones and pearls.

This carat weighs four grains, but something lighter than the grains of other weights. Each of these grains is subdivided into $\frac{1}{2}$, $\frac{1}{3}$, $\frac{1}{4}$, $\frac{1}{5}$, &c.