(Note. It is to be understood that this does not represent the
Arizona production. No figures as to that are available.)
The value of the imports of precious stones into the United
States in 1914 was $19,211,084, showing a decrease of $26,220,914
from 1913.
ESSENTIAL PROPERTIES OF GEMS.
Gems are certain minerals which, by reason of their brilliancy,
hardness and rarity, are valued for personal decoration; the term is
extended to include pearl. _ (Definition from Encyclopedia Brit-
tanica). In a restricted sense the term is applied only to precious
stones after they have been cut and polished as jewels, while in their
raw state, the minerals are conveniently called gem stones.
The general properties which determine the value of a gem are:
(1) hardness; (2) specific gravity; (3) crystalline form and
cleavage; (4) color; (5) optical properties, refraction and dispersion,
person.
(1) Hardness A high degree of hardness is a desirable property
of a gem, for no matter how brilliant and beautiful a mineral may
