# A Treatise on Diamonds, and Precious Stones/Chapter 1/Section 3

SECT. III.
Remarks on the Purchase and Sale of Diamonds.
The following observations may be found useful to those who are desirous of purchasing or disposing of diamonds.
I once possessed a brilliant of eight carats, well proportioned, and extremely fine, with the exception of two spots of what is technically called foul; one was in the centre of the table, not larger than a small pin's head, and the other at the corner of the table. It was sold for £380; but had it been quite perfect, it would have obtained from £550 to £600, or more.
The Nassuc diamond, valued at thirty thousand pounds, and which I modelled on ​its arrival in England, belonging to the East India Company, weighs seventy-nine and a half carats, and if it were a well-proportioned stone, and cut in brilliant, it would doubtless be much more valuable. This example may serve to shew, that it is not merely because the substance is a diamond that it commands a high price; but because, as a diamond, it must have all the qualities that art can bestow, and be faultless.
There is an extensive traffic in these precious substances, exclusive of the regular trade between the jeweller and the merchant. A person possessing a suit of brilliants may be inclined to part with them from necessity, or other causes. This occurs so frequently, that diamonds to a great amount are continually disposed of in a private way. If, as it frequently happens, necessity be the motive, a degree of caution and delicacy is to be observed, which renders any competition of pur​chasers impossible, and prevents the article from obtaining its true value. In this sort of confidential bargain, it is to be lamented that the seller is almost compelled to accept such terms as may be offered.
Some time ago, a person was obliged, or perhaps persuaded to dispose of a brilliant necklace that had been received as a gift. The lady applied to ___, in whom she had implicit confidence. The result of the interview was, that they purchased the article for a sum under £300. Being themselves in want of money, they took the stones from the setting, and sold them by weight for nearly double the purchase-money.
Another instance is within our knowledge of a lady having purchased a pair of ear-ornaments (tops and drops) for £250; after a lapse of some time she determined to sell them, and was only offered £60! She afterwards ​went to a Diamond Merchant, who weighed the drops, and offered £ 120 for them alone, which was accepted.
A lady became possessed of a brilliant necklace by legacy, on which it was necessary to pay the duty. A jeweller was referred to, who valued them at £1,600, and the duty was paid on that sum. The same neck-lace was soon afterwards disposed of, and estimated only at £800, in exchange for other articles!
It may here be observed, that the great difficulty which. presents itself to those who may be delicately situated, and wish to dispose of their Diamonds, arises from their not knowing ​that they are sold by weight. Diamonds free from flaws have generally a regular price: they are easily taken out of the setting, and a working jeweller would do it in a few minutes; but if the brilliants. are very thin it is the safest way to put them, fora few hours, in nitric acid, when they become loose by the acid dissolving a portion of the silver cramps that confine them.
Snuff-Boxes and portraits set with brilliants are generally composed of thin Diamonds, which present a large surface.
The fineness, as well as the weight of Diamonds, as before stated, must be considered in estimating their value. Suppose a half hoop ring to be composed of five stones, allow the centre one to weigh three grains; those next to it 24 grains each, and the others, 2 grains each: here would be three carats of Diamonds, which, if fine, would cost the retailer from £18 ​to £20, but if they were in any degree inferior, would not cost more than from £14 to £16,
To judge of Diamonds accurately, they should be laid loose in a good light, upon a sheet of white paper, on which their purity and brilliancy are bestseen, their proportions ascertained, and the tinges of color, specks, flaws, foul, &c. most visibly exposed. This is the proper and fair mode of exhibiting them for sale.
Peculiar shaped brilliants, calculated for ear-drops, sell at capricious prices and are always in demand. It may be remarked that a dealer going among the merchants to purchase stones of peculiar forms, and ofacertain weight, will have to pay in many cases ten per cent. more than if he boughtthem in the usual course of dealing.
Two brilliants, single cut but finely propor​tioned, came into my possession a few years ago, one of which was 174½ grains, the other 184 grains: they had the smallest possible tinge of yellow, and were therefore what is termed off color; one sold for £117, the other for £125.
A lot of brilliants, single cut, from one to two grains each, was consigned to me for sale. At the time I could not obtain more than five guineas and a half per carat. They were worth more, as rough Diamonds could not be bought and manufactured for sale at the same price. They were in a small degree off color, but would set to great advantage in jewellery.
A necklace was sent to me from Spain, for which I allowed £120: the diamonds had a large surface, and black spots appeared through the table to represent the collets. I was aware that they were very thin, and of the description called lasques. Taking the stones ​from their setting, I found that they were upon foil; many of them brown, and so thin, that the best were only fit for making rose-shaped stones: the others I sold as bort, and found it difficult to obtain their cost.
An apparently beautiful brilliant, of a pink color, was sent to me, which I estimated at three carats, A great price was asked, and would have been given; but on drawing the gem it proved to be lightly tinged with color, and set on pink foil.
A rough diamond of 15: carats, apparently very fine, was consigned to me, valued at £400, it was judged it would be offcolor. I sold it to a Dutch merchant for £280; its form was a very regular octahedron.
It often occurs that alarge rough diamond, of a brown appearance, is only bad in a parti​cular part—but from the high refractive quality of the gem, it appears discolored all over.
A Lot of eighteen most beautiful rich diamonds, all of very high lustre, was sent to me. They had a slight tinge of yellow, and weighed seventeen carats. The price asked was three pounds per carat; they were afterwards bought at forty-nine shillings, not one of them made a white brilliant; they were all off color, and it was doubtful whether they would be sold at a price to cover the cost.
Three rough stones were consigned to me; they weighed almost exactly 5 carats each, together 15½ carats, they were all fine, and would cut free from flaws; though one exhibited some indication of not being of the purest water. Their forms were favorable for cutting to advantage, and making spread stones; they sold for £120, which was considered an excellent price: they would weigh together, when made into brilliants, from 32 to 34 grains.
​I received a large fragment of diamond, weighing above 12 carats: one end was foul and full of flaws; I split it off, and discovered the foul was owing to a triangular hole, the sides of which were covered with black earth.
Yellow brilliants, if fine, are generally extremely lively, and suit the purposes of the jeweller in composing fancy articles. When of from one to two grains, they are usually from four to five pounds per carat; being inferior in value to the pure gem. I have known a yellow brilliant of 7½ carats, to sell publicly for £240,
Brilliants tinged dull green or brown are much depreciated by such colors. Cloudy diamonds are also of little value; hut those of fine colors—pink, red, blue, or green, are eagerly sought for by connoisseurs,
Diamonds at this time are considered very low, there are many offered for sale but few ​buyers; consequently some lots of brilliants, in the hands of needy sellers, may be bought at ten per cent. below the present average price; observing, generally, that diamonds were considerably higher a few years ago.
Brown diamonds are often brought from India of considerable size and brilliancy, but they rarely sell for their cost: indeed, cloudy and bad brilliants, or roses, have scarcely any commercial value, although, however, they may often be highly estimated by the possessor.
Inferior brilliants may be bought very low; I have now a lot before me, in which are some of two grains, for which I would not give four guineas per carat, and roses of the same denomination may be bought at forty or fifty shillings.
Bad discolord diamonds are sold to break into powder, and may be said to have a more ​extensive sale than brilliants with. all their captivating beauty. In many operations of art they are indispensible; the fine Cameo and Intaglio owe their perfection to the diamond, with which alone they can be engraved. The beauty of the Onyx would yet remain dormant, had not the unrivalled power of the diamond been called forth to the artist's assistance, The carnelian, the agate, or Cairn-Gorm cannot be engraved by any other substance; every crestor letter cut on hard stone, is indebted to the diamond—This is not all, for without it blocks of crystal could not be cut into slices for spectacles—agate for snuff-boxes, &c.
In the breaking of Diamonds, bits, shivers, an eighth of an inch long, sometimes occur, which if properly proportioned are in demand and used for drilling holes in glass, china, &c.
​Diamond merchants have adopted a very delicate and highly honorable method of offering polished Diamonds for sale—they employ confidential men, to take: brilliants of various qualities, in separate lots, to the trade; their weight and price are generally marked on the paper in which they are folded. If a particular parcel is found desirable, but thought to be charged too high, an offer a little lower may be made: in which case the intended purchaser is allowed to affix his seal upon the lot, until the principal is made. acquainted; then, if the terms are not approved, the employee returns with them, and requests the seal to be broken. Thus, during the negotiation, which often continues several days, thelot cannot be exhibited or hacknied through the trade.