False Precious Stones: Natural

Under the name of false precious stones, there are two kinds of productions which are essentially different--the one natural, the other artificial.

The first comprehends stones sufficiently hard to resist the file; they are generally quartz, either hyaline or variously coloured.

The second consists of artificial compositions of the nature of glass.

There is an intermediate order, the productions belonging to which, if well executed, are especially calculated to deceive, and are used to great extent in the East Indies. They are called semi-stones, or doublets.

It is of some importance to examine this subject, because there is a prevalent belief that all false stones necessarily have glass as their base, and are consequently of little hardness. People often say, when their rubies or their topazes are declared false, "But, see, here is a file; try to scratch these stones; you will not succeed." Very true; but submit any piece of quartz to the same test, and the result will be the same.

Since, as we have said, hyaline or variously coloured quartz is very abundant in nature, it is easy to procure, at insignificant prices, stones that perfectly resist the file, and show, often in a remarkable manner, the whole series of colours that we admire in real precious stones.

Stones of this kind are very abundant in commerce; it might be said that, with few exceptions, all those designated as occidental are of this character, and possess consequently hardly any value. Another deception of the same kind consists in passing off a stone of a certain nature and a certain value, for another stone of a different nature and a much higher value.

The colourless varieties of sapphire and topaz, which in density, in hardness, and in refractive power differ but little from the diamond, are frequently cut into roses and brilliants, and sold for diamonds. A proof of this fact is furnished by the commercial price of the colourless topaz, which is much greater than it could obtain as topaz. It is valued in the secret hope that after cutting it may be sold for diamonds.

At the present day there are means--such as the scales for determining specific gravity, polariscopes, &c.--for distinguishing with mathematical certainty the diamond from the sapphire or topaz; but these tests are of modern origin; and in the middle ages not only colourless topazes, but those whose tint had been removed in different ways, principally by the action of fire, frequently passed current for diamonds. Nay more than this, under the influence of the ideas that then prevailed concerning transmutation, the successful experimenters believed that they had actually transformed rubies and topazes into diamonds.