whereof,
an instance is first given in rough diamonds ; on which account it will
be necessary to lay down a general price, which is supposed to be £2
per carat; meaning, the whole species, good and bad blended together,
which are worthy the expence of manufactory. For example, suppose the
value of a rough diamond of two carats, at the rate of £2 per carat,
should be required; the rule is, first, to multiply 2 by 2, which makes
4, the square of its weight; then multiply the product of 4 by £2, the
price of one carat, that makes £8, which is the true value of a rough
diamond of 2 carats.
To
make this rule applicable to manufactured diamonds, it will be
necessary to ascertain what waste, or loss of weight, will be sustained
in manufacturing them. And here it may be advanced as a matter of fact,
that half the weight will be lost; consequently, doubling the weight
of any manufactured diamond, renders the rule of the same use to show
their value. This loss is to be understood to relate to the general
manufactory of brilliant and rose diamonds, in the most perfect manner.
To that end,
