Jean-Baptiste Tavernier’s Travels In India

Rule for ascertaining the proper price of a diamond of whatsover weight it may be, from 3 up to and above 100 carats
(via Jean-Baptiste Tavernier’s Travels In India / V Ball / Edited by William Crooke)

I do not mention diamonds below 3 carats, their price being sufficiently well known. It is first necessary to ascertain the weight of the diamond, and next to see it is perfect, whether it is a thick stone, square-shaped, and having all its angles perfect; whether it is of a beautiful white water, and bright, without points, and without flaws. It if is a stone cut into facettes, which is ordinarily called ‘a rose’, it is necessary to observe whether the form is truly round or oval; whether the stone is well-spread, and whether it is not a lumpy stone; and, moreover, whether it is of uniform water, and is without points and flaws, as I described the thick stone.

A stone of this quality, weighing 1 carat, is worth 150 livres or more, and supposing it is required to know the value of a stone of 12 carats of the same degree of perfection, this is how it is to be ascertained: square the 12, this amounts to 144; next multiply 144 by 150, i.e the price of 1 carat, and it amounts to 21,6000 livres—12 x 12 x 150 = 21600. This is the price of a diamond of 12 carats.

But it is not enough to know the price of only perfect diamonds, one must know also the price of those which are not so; this is ascertained by the same rule, and on the basis of the price of a stone of 1 carat. This is an example: suppose a diamond of 15 carats which is not perfect, the water being not good, or the stone badly shaped, or full of spots or flaws. A diamond of the same nature, of the weight of 1 carat, would not be worth more than 60 or 80 or 100 livres at the most, according to the beauty of the diamond. You must then square the weight of the diamond, i.e 15 carats, and next multiply the product 125 by the value of the stone of 1 carat, which may for example be 80 livres, and the product, which is 10000 livres, is the price of the diamond of 15 carats.

It is easy to see from this the great difference in value between a perfect stone and one which is not so. For if this stone of 15 carats had been perfect, the second multiplication would be by 150, which is the price of a perfect stone of 1 carat, and then it would amount not to 10000 livres, but to 33750 livres, i.e. to 23750 livres more than an imperfect diamond of the same weight.

According to this rule, the following is the value of the two largest among the cut stones in the world—one of them in Asia belong to the Great Mogul, the other in Europe belonging to the Grand Duke of Tuscany—as will be seen by the subjoined figures.

The Great Mogul’s diamond weighs 278 9/16 carats, is of perfect water, good form, and has only a small flaw which is in the edge of the basal circumference of the stone. Except for this flaw the first carat would be placed at 160 livres, but on that account I do not estimate it at more than 150, and so calculated according to the above given rule it reaches the sum of 11,723,278 livres, 14 sols, and 3 liards. If this diamond only weighed 279 carats, it would have been worth 11,679,150 livres only, and thus these 9/16ths are worth 47,128 livres, 14 sols, 3 liards.

The Grand Duke of Tuscany’s diamond weighs 139½ carats, is clear, and of good form, cut on all sides into facettes, and as the water tends somewhat to a citron color, I estimate the first carat at only 135 livres, from which the value of the diamond ought to be 2.608,335 livres.

In concluding the remarks which I have made in this chapter, I should say that in the language of the miners the diamond is called iri; that in Turkish, Persian, and Arabic it is called almas, and that in all the languages of Europe it has no other name than diamond.

This, then, in a few words is all that I have been able to discover with my own eyes in regard to this subject during the several journeys which I made to the mines; and if by chance some other has written or spoken of them before me, it can only have been from the reports which I have made of them.