PROPERTIES AND TESTS FOR DIAMONDS
ments extended over four years, and in that time no stone which had been changed to blue-white reverted to its original hue.
are measured by a tiny unit of weight called a carat. There are 2,268
metric carats in a pound, or about 142 carats to the ounce.
Specifically, the metric carat is equal to .2 grams; this is about the
size of an average pea. Most of the stones passing through the office
of the Diamond Corporation in London are less than one carat, some of
them are as small as 200 to the carat. A good one carat stone in any
jeweler's shop will cost three hundred and seventy-five dollars or
more; but you can buy a carat of small diamonds for as little as
seventy-five dollars. The word, carat, is said to be derived from the
name of a seed which was once used in the East as a weight.
rings usually have the diamond in a gold ring. The ring which contains
22/24 of pure gold, is called 22 carats fine, or 22 carat gold. The
lower standard used for watch cases which contain 18/24 of pure gold is
called 18 carats. The carat used in this sense has therefore no
absolute weight; it merely denotes a ratio. This, however, is not the
case with the carat used for weighing diamonds and other precious
stones, which has a fixed weight.