The chemistry, properties and tests of precious stones

Zircon appears to have been first discovered by Klaproth in 1789, in the form of an earth, and six years later he found that the stone hyacinth contained a similar substance, bo...

There are certain stones and other minerals which, owing to their possession of numerous microscopically fine cavities, of a globular or tubular shape, have the appearance of "r...

To recapitulate certain of the facts respecting the diamond.--This wonderful gem has the distinction amongst precious stones of being unique; though many are composed of two, th...

As existing in a state of nature precious stones do not, as a rule, exhibit any of those beautiful and wonderful properties which cause them to be so admired and sought after as...

We now arrive at the point where it is necessary to discuss the manufacture and re-formation of precious stones, and also to consider a few of the tests which may be applied to...

By cleavage is meant the manner in which minerals separate or split off with regularity. The difference between a break or fracture and a "cleave," is that the former may be any...

Colour is one of the most wonderful effects in nature. It is an attribute of light and is not a part of the object which appears to be coloured; though all objects, by their che...

Though the origin, formation, composition, characteristics and tests of each stone will be examined in detail when dealing with the stones seriatim, it is necessary to enquire i...

The fixing of the specific gravity of a stone also determines its group position with regard to weight; its colour and other characteristics defining the actual stone. This is a...

Before proceeding to the study of precious stones as individual gems, certain physical properties common to all must be discussed, in order to bring the gems into separate class...

Probably the most important of the many important physical properties possessed by precious stones are those of light and its effects, for to these all known gems owe their beau...

What constitutes a precious stone is the question which, at the onset, rises in the mind, and this question, simple as it seems, is one by no means easy to answer, since what ma...

The word "electricity" is derived from the Greek "elektron," which was the name for amber, a mineralised resin of extinct pine-trees. It was well-known to the people of pre-hist...

The method of testing is very simple. A representative selection of the above stones, each with a sharp edge, is kept for the purpose of scratching and being scratched, and thos...

Another method of isolating certain stones is by the action of heat-rays. Remembering our lessons in physics we recall that just as light-rays may be refracted, absorbed, or ref...

Hardness is perhaps one of the most important features in a stone, especially those of the "gem" series, for no matter how colour, lustre, general beauty and even rarity may ent...

_Hardness._ _Specific Gravity._ (See Chapter VII.) (See Chapter VIII.) Beryl 7-3/4 2.709-2.810 Diamond 10 3.502-3.564 Dichorite (Water Sapphire) 7-7-1/2 4.049-4.060 Disthene (Ky...

_Hardness._ _Specific Gravity._ (See Chapter VII.) (See Chapter VIII.) Diamond 10 3.502-3.564 Garnet 6-1/2-7-1/2 3.400-4.500 Jet 3-1/2 1.348 Onyx (a variety of Chalcedony) 6-1/2...