Gem-Stones and Their Distinctive Characters

Although many of the gem-stones have been endowed by nature with brilliant lustrous faces and display scintillating reflections from their surfaces, yet their form is never such...

Although none of the substances considered in this chapter come within the strict definition of a stone, since they are directly the result of living agency, yet pearl at least...

The whole of the diamonds known in ancient times were obtained from the so-called Golconda mines in India. Golconda itself, now a deserted fortress near Hyderabad, was merely th...

It is one of our earliest experiences that different substances of the same size have often markedly different weights; thus, there is a great difference between wood and iron,...

The methods available for the measurement of refractive indices are of two kinds, and make use of two different principles. The first, which is based upon the very simple relati...

The species to be considered in this chapter includes the varieties emerald and aquamarine, as well as what jewellers understand by beryl. It has many incontestable claims on th...

The number of diamonds which exceed a hundred carats in weight when cut is very limited. Their extreme costliness renders them something more than mere ornaments; in a condensed...

The optical phenomenon presented by many gem-stones is complicated by their property of splitting up a beam of light into two with, in general, differing characters. In this cha...

Ranking in hardness second to diamond alone, the species known to science as corundum and widely familiar by the names of its varieties, sapphire and ruby, holds a pre-eminent p...

The important group of minerals which are known under the general name of garnet provides an apt illustration of the fact that rarity is an essential condition if a stone is to...

The initial step in the examination of a crystallized substance is to determine its physical characters and to resolve it by chemical analysis into its component elements; the f...

Diamond has held pride of place as chief of precious stones ever since the discovery of the form of cutting known as the ‘brilliant’ revealed to full perfection its amazing qual...

The small green stones which accompany the diamond in South Africa have been cut and put on the market as ‘green garnet.’ They are, however, in no way connected with garnet, but...

When white light passes through a cut stone, colour effects result which arise from a variety of causes. The most obvious is the fundamental colour of the stone, which is due to...

Although the commonest and, in its natural form, the most easily recognizable of mineral substances, quartz nevertheless holds a not inconspicuous position among gem-stones, bec...

With the single exception of opal, the whole of the principal mineral species used in jewellery are distinguished from glass and similar substances by one fundamental difference...

It is obvious that, since a stone suitable for ornamental use must appeal to the eye, its most important characters are those which depend upon light; indeed, the whole art of t...

Space will not permit of more than a few words concerning the more prominent of the numerous mineral species which are employed for ornamental purposes in articles of virtu or i...

Tourmaline is unsurpassed even by corundum in variety of hue, and it has during recent years rapidly advanced in public favour, mainly owing to the prodigal profusion in which n...

Beauty, durability, and rarity: such are the three cardinal virtues of a perfect gem-stone. Stones lacking any of them cannot aspire to a high place in the ranks of precious sto...

Chrysoberyl has at times enjoyed fleeting popularity on account of the excellent cat’s-eyes cut from the fibrous stones, and in the form of alexandrite it meets with a steadier,...

Topaz is the most popular yellow stone in jewellery, and often forms the principal stone in brooches or pendants, especially in old-fashioned articles. It is a general idea that...

Zircon, which, if known at all in jewellery, is called by its variety names, jargoon and hyacinth or jacinth, is a species that deserves greater recognition than it receives. Th...

That opal in early times excited keen admiration is evident from Pliny’s enthusiastic description of these stones: “For in them you shall see the burning fire of the carbuncle,...

Though not usually accounted precious among European nations or in Western civilization in general, jade was held in extraordinary esteem by primitive man, and was fashioned by...

Spinel labours under the serious disadvantage of being overshadowed at almost all points by its opulent and more famous cousins, sapphire and ruby, and is not so well known as i...

Till a few years ago scarcely known outside the ranks of mineralogists, spodumene suddenly leaped into notice in 1903 upon the discovery of the lovely lilac-coloured stones (Pla...

Every possessor of a diamond ring is aware that diamond easily scratches window-glass. If other stones were tried, it would be found that they also scratched glass, but not so r...

The names in popular use for the principal gem-stones may be traced back to very early times, and, since they were applied long before the determinative study of minerals had be...

The system in use for recording the weights of precious stones is peculiar to jewellery. The unit, which is known as the carat, bears no simple relation to any unit that has exi...

The beryl glass mentioned in the previous chapter marks the transition stage between manufactured stones which in all essential characters are identical with those found in natu...

The beautiful bottle-green stone, which from its delicate tint has earned from appreciative admirers the poetical _sobriquet_ of the evening emerald, and which has during recent...

Of all the opaque stones turquoise (Plate XXIX, Fig. 17) alone finds a prominent place in jewellery and can aspire to rank with the precious stones. The colour varies from a sky...

It has been already stated that whenever light in one medium falls upon the surface separating it from another medium some of the light is reflected within the first, while the...

Chalcedony and agate, and their endless varieties, are composed mainly of silica, but the separate individual crystals are so small as to be invisible to the unaided eyesight, a...

Though second to none among minerals in scientific interest, whether regarded from the point of view of their crystalline characters or the important part they play in the forma...

The definite orientation of the molecular arrangement of crystallized substances leads in many cases to attributes which vary with the direction and are revealed by the electric...

This species comes near beryl in chemical composition, being a silicate of aluminium and beryllium corresponding to the formula Be(AlOH)SiO_{4}, and closely resembles aquamarine...

Though usually opaque, this oxide of tin, corresponding to the formula SnO_{2}, has occasionally, but very rarely, been found in small, transparent, yellow and reddish stones su...

Two forms of natural glass have been employed for ornamental purposes. Obsidian results from the solidification without crystallization of lava, and corresponds in composition t...