The Real Gem Stone Which Not So Easy To Imitate, The Sapphire
The Sapphire is not so easy to imitate, as its hardness exceeds that of the ruby, and imitations containing its known constituents, or of glass, are invariably softer than the natural stone.
As before remarked, almost any form of corundum other than red is, broadly, called sapphire, but giving them their strictly correct designations, we have the olivine corundum, called "chrysolite" (oriental), which is harder than the ordinary or "noble" chrysolite, sometimes called the "peridot."
The various yellow varieties of corundum take the name of the "oriental topaz," which, like most, if not all, the corundum varieties, is harder than the gem which bears the same name, minus the prefix "oriental."
Then we have the "amethyst" sapphire, which varies from a red to a blue purple, being richer in colour than the ordinary amethyst, which is a form of violet-coloured quartz, but the corundum variety, which, like its companions, is called the "oriental" amethyst, is both rarer and more precious.
A very rare and extremely beautiful green variety is called the oriental emerald. The oriental jacinth, or hyacinth, is a brown-red corundum, which is more stable than the ordinary hyacinth, this latter being a form of zircon; it changes colour on exposure to light, which colour is not restored by subsequent retention in darkness.
The blue sapphire is of all shades of blue, from cornflower blue to the very palest tints of this colour, all the gradations from light to dark purple blues, and, in fact, so many shades of tone and colour that they become almost as numerous as the stones.
These stones are usually found in similar situations to those which produce the ruby, and often along with them.
The lighter colours are usually called females, or feminine stones, whilst the darker ones are called masculine stones.
Some of these dark ones are so deep as to be almost black, when they are called "ink" sapphires, and if inclining to blue, "indigo" sapphires, in contradistinction to which the palest of the stones are called "water" sapphires.
The colouring matter is not always even, but is often spread over the substance of the stone in scabs or "splotches," which rather favours imitation, and, where this unevenness occurs, it may be necessary to cut or divide the stone, or so to arrange the form of it that the finished stone shall be equally blue throughout.
In some cases, however, the sapphire may owe its beauty to the presence of two, three or more colours in separate strata appearing in one stone; such as a portion being a green-blue, another a cornflower blue, another perfectly colourless, another a pale sky blue, another yellow, each perfectly distinct, the stone being cut so as to show each colour in its full perfection.
This stone, the sapphire, is hardness No. 9 (see "Hardness" table), and therefore ranks next to the diamond, which makes it a matter of great difficulty to obtain an imitation which is of the same specific gravity and of the same degree of hardness, though this has been done.
Such stones are purchasable, but though sold as imitations at comparatively low price, and the buyer may consider them just as good as the real gem, to the experienced eye they are readily detectable.
By heating a sapphire its blue colour slowly fades, to complete transparency in many cases, or at any rate to so pale a tint as to pass for a transparent stone.
Valuable as is the sapphire, the diamond is more so, and it follows that if one of these clear or "cleared" sapphires is cut in the "rose" or "brilliant" form—which forms are reserved almost exclusively for the diamond—such a stone would pass very well as a diamond, and many so cut are sold by unscrupulous people as the more valuable stone, which fraud an expert would, of course, detect.
Sapphires are mentioned by Pliny, and figure largely in the ancient history of China, Egypt, Rome, etc.
The Greeks dedicated the sapphire specially to Jupiter, and many of the stones were cut to represent the god; it also figured as one of the chief stones worn by the Jewish High Priest on the breast-plate.
Some stones have curious rays of variegated colour, due to their crystalline formation, taking the shape of a star; these are called "asteriated," or "cat's eye" sapphires.
Others have curious flashes of light, technically called a "play" of light, together with a curious blue opalescence; these are the "girasol."
Another interesting variety of this blue sapphire is one known as "chatoyant"; this has a rapidly changing lustre, which seems to undulate between a green-yellow and a luminous blue, with a phosphorescent glow, or fire, something like that seen in the eyes of a cat in the dark, or the steady, burning glow observed when the cat is fascinating a bird—hence its name.
This is not the same variety as the "asteriated," or "cat's eye" or "lynx eye" mentioned above.
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