ed upon the use of this
unit. Its use in the United States became general July 1, 1913. It is by
definition exactly one fifth of a _gram_ (the unit of weight of the
_Metric System_ of weights and measures). Its relation to the _grain_ is
that there are 3.08+ grains in the metric carat. The carat in use in
this country up to a few years ago was about 2-1/2% heavier than the
present metric carat. It was equal to .2053 grams instead of .2000
grams (1/5 gram). The carats of countries not using the metric carat
vary considerably, but yet approximate the metric carat somewhat nearly.

Thus, that in use in Great Britain was .2053 g., in Amsterdam .2057 g.,
in Berlin .20544 g., in Lisbon .20575 g., and in Florence 0.1972 g. The
latter was the only one that was under the metric carat. The change to
the metric carat was desirable, as it unified the practice of weighing,
which not only varied in different countries, but even in the same
country. Thus there was no very exact agreement among the makers of
diamond weights in the United States prior to the adoption of the metric
carat. One man's carat was a bit heavier or lighter than another's. With
a definite and simple relationship to the standard gram there is now no
excuse for any variation in weights. The Bureau of Standards at
Washington affords manufacturers every facility for standardizing their
weights.

THE DECIMAL SYSTEM OF SUBDIVISION OF THE CARAT. With the adoption of the
metric carat the custom of expressing parts of a carat in common
fractions whose denominators were powers of the number 2 (1/2, 1/4, 1/8,
1/16, 1/32, 1/64) was discarded as awkward and slow for computation and
the decimal system of subdivision was adopted. Thus the metric carat is
divided into tenths and one hundredths. It is customary, however, to sum
up the one hundredths and express them as the total number of one
hundredths and not to express them as tenths. Thus, a stone of 2.57
carats is said to weigh "two and fifty-seven hundredths carats." The
decimal system of subdivision of the carat makes the figuring of values
simpler where no tables are handy. Of course, new tables were at once
prepared when the new carat was adopted and they afford a rapid means of
ascertaining the value of a stone of any weight when the price per carat
is known. Should it become necessary to convert the weight of a stone
from its expression in the old system to that of the new, one need only
get 1.02-1/2% of the old weig