A Treatise on Diamonds, and Precious Stones/Chapter 1/Section 2
SECT. II.
Commercial Value of Diamonds.
In the great or wholesale trade there is but little fluctuation in the price of those diamonds which may be termed stones in general demand. I will begin with brilliants, from a grain, to two and a half grains each. Such brilliants, double cut, and what may be termed fine, are worth from seven to eight pounds, per carat. Needy sellers may take ten per cent. less for cash; but this is the general average price for a lot of ten, twenty, or fifty carats of well-made stones, if the quality be good.
Brillliants, from two grains to three, may be bought m lots, at from seven guineas to eight pounds, per carat. It is to be understood, that diamonds in a lot are never all quite free from faults, hence there may arise a difference of ten per cent. in the price. Stones of three grains, if fine and perfect, are always in demand, at eight or nine pounds per carat.
Brillliants, from three grains to four, if very fine, and well proportioned, are worth from eight guineas to nine pounds, per carat, Those of a carat each, if very fine, and well selected, are now worth nine guineas to ten pounds. Three years ago, I offered twelve pounds each for eight, and could not obtain them.
Brilliants, from five grains to six, if pure, are worth from thirteen to fourteen pounds; if perfectly fine, and of the full weight of six grains, they are worth seventeen to eighteen pounds each; I have, for such, paid twenty pounds.
Brilliants of two carats each, are worth from twenty-seven to thirty pounds, Stones of this weight, if well proportioned, are considered of a fine size, and well calculated for pins, or the centre of clustres. Indeed, well proportioned diamonds from six grains to two carats each, are always in demand, and are retailed at from twenty to thirty-five pounds, each, according to their degree of perfection, or as the retailer may think fit to charge them,
For brilliants of three carats, if tine and well formed, from seventy to eighty pounds may be obtained. Stones of this size and larger are more liable to capricious fluctuations of price than the smaller ones before named, being chiefly required for the centre stones of saleable necklaces,
Brilliants of four carats, if fine, are worth from £100 to £130. I have sold stones, single cut, a little off color, of this weight at eighty guineas. I possessed one of seventeen grains, perfectly white, having a surface as large as that of a seven carat stone ought to be, it was consequently very thin, but being much in request on account of its great spread or surface, it was sold for £160.
Brilliantsof five carats are not frequently met with in general trade, and are variable in price, as the dealers exact more if they know that such stones are wanted, than they would in the regular course of business. The prices may be said to vary from £180 to £200.
Brilliants of six carats, as before-stated, are not common; they are suitable for centre stones of expensive necklaces, and single stone rings: if perfect and well-shaped, they sell for £230 to £250, or more.
For estimating the value of peculiarly fine diamonds, there is no fixed standard; the rule already published may, however, serve as a sort of guide.
Rough Diamonds, selected as fine, and well formed for cutting, may be estimated as follows: Square the weight of the stone, multiply the product by two, and the result will be the value in pounds sterling. This rule, however, is by no means in general use. Brilliants, ifgfine, may be estimated by squaring the weight in carats, and multiplying the product by eight, which will give the amount in pounds sterling.[1]
- ↑ This is an Indian rule, and is only applicable in some cases: but if there should be any natural imperfection in the stone or brilliant, or even if it be ill formed although pure, the multiplier must be taken at a much lower number; and if superlatively fine, it may be taken, in some peculiar cases, proportionably higher.