I Carat's Weight in Various Localities 303
semi-precious
stones in the trade are reckoned in pennyweights. Pearls are weighed
and their values calculated by the grain (1/4 carat). Diamonds are
designated in the trade as " grainers," " two grain-ers," etc.; a "
four grainer " is a diamond weighing one carat. The practice in the
United States has been to calculate the carat at 205 milligrams or
3.210 grains Troy. The new metric carat, which will probably eventually
become the universally recognised standard, will weigh 200 milligrams
or 3.130 grains.
CRYSTALLOGRAPHY
SYSTEMS OF CRYSTALLINE FORM
