72 PRECIOUS STONES.
The carat is divided into 1/2, 1/4, 1/8, ... 1/64 of
the carat. The table of weights of a jeweller's balance should contain
from the weight of a thousand carats to these fractions.
The
balance employed by dealers in precious stones is a simple little
balance which is held in the hand: and yet "such is the experienced
quickness of the lapidary," says M. Helphen, "that the balance of the
assayer will never find him wrong by even the 64th part of a carat."
Rough
crystallized diamonds are valued at from l6-1/2 to 19 dollars
thecarat.for assorted lots containing no diamonds of more than one
carat. Above this weight prices are a different affair.
The
rule made known two hundred years ago by Tavernier, that "the prices of
two diamonds are proportioned to the squares of their weights," is
endorsed bysome modern lapidaries. According to this rule, since a
one-carat stone of the first water, well cut and without flaws, is
valued at about $93, a stone of two carats should be worth four times
that, or $372; and one of three carats, nine times as much, or $837.
But
statistics show that this rule, which was quite true in the time of
Jeffries and Tavernier, is no longer applicable; it assigns to diamonds
a higher price than in commerce they really bring.
A table is given here, which not only establishes this fact, but which also furnishes other interesting