The color-suite of the mineral is much more extensive and varied than has been generally admitted by mineralogists. We are led to infer from their works that white is the prevailing hue of the gem; but Beudant declares that perfect limpidity and whiteness is rare comparatively, and that the stone is generally affected with yellowish or brownish tints. But what becomes of the vast numbers of these clouded or tinged and inferior gems, if the mines yield so many of them in comparison with the snow-white? Are they consumed in polishing others, or expended in the arts, or have the lapidaries secret processes by which these objectionable tints are expunged from the stone?
Barbot, the French jeweller, declares that, by means of certain particular and energetic agents, aided by a proper degree of heat, he is able to remove the greens of all shades, the light-red, and the yellow, when the coloring matter is superficial, or even situated between the external laminæ. We are inclined to believe Barbot in this particular reference, especially as he admits that he is unable to change much the deep-yellow, the brown, and the smoky-tinted stones. Of the yellow tints, the diamond affords the most beautiful examples, and far surpasses in variety all the other gems, with the exception perhaps of quartz. To the yellow topaz it is decidedly superior in its range of shades, and in some of its chrome-like tints it is without an equal among the gems. This hue of chrome mixed with a faint tinge of green is a delicate, yet gorgeous, shade, and is not often seen. Stones of a canary-yellow are quite common, and perfect resemblances to the Brazilian topaz are not rare. From these hues they pass insensibly into brown and black. The transparent light-brown stones are often modified in hue when exposed to the action of heat, and some of them exhibit remarkable changes of color. M. Halpen, in 1866, exhibited to the French Academy of Sciences a singular diamond of this description. It was a stone of sixty grains weight, and of a whitish hue tinged slightly with brown. But when it was exposed to the action of heat it changed its tint to a fine rose-color, and retained it for six or eight days, when it gradually returned to its natural hue. This remarkable effect was not an accidental result, but was tried five times at the Academy with success and without injury to the stone. In other colored diamonds the action of fire often produces permanent effects, and sometimes a brownish hue is converted into a decided red color. Buckman saw a diamond with a large brown spot in its interior change to a beautiful red, like that of the Balais ruby, after the stone had been placed in borax and exposed to a red heat. Another stone, however, of similar appearance, likewise exposed, changed to a permanent black, to the great injury of the gem and dismay of the experimenter. The red varieties of this mineral are rarely of deep tints, but when they exhibit a decided red color they form the most gorgeous of gems. The largest and finest of this description known is the ten-karat stone purchased by the Emperor Paul of Russia for one hundred thousand roubles. This gem may be considered the marvel of the mineral kingdom. The princely collection of the late Mr. Hope possessed one of a blood-red garnet shade, also a fine twelve and a half karat stone of an apricot hue, besides several others of a beautiful hyacinth red, or of a lilac pink.
The celebrated cabinet of gems belonging to the late Marquis de Drée contained a large and beautiful rose-colored diamond. Prince Riccia, of Naples, acquired in 1830 a very fine rose-colored brilliant of fifteen karats weight. M. Halpen, in 1838, exhibited a magnificent gem of this description of twenty-two and a half karats. Among the crown jewels of France there are several splendid brilliants of a peach-blossom hue, and there are also quite a number to be seen among the princely caskets of Europe. It is, however, somewhat remarkable that this gem, although possessing several shades of red, never, or very rarely, occurs of a decided violet or purple color. Diamonds of a light aqua-marine of greenish and bluish tints are not rare, but those of a positive grass-green color are uncommon. Perfect stones of decided green form the most magnificent gems of this color. The velvety green flashed forth by the extraordinary power of the stone surpasses beyond comparison the finest emeralds with their duller reflections. In fact, we may term the splendid green diamond of forty karats, now in the Green Vaults at Dresden, as being one of the five paragons among all the gems of the world.
In the Museum of Natural History in Paris there are some small diamonds of very fine shades of green, which were collected by the celebrated Werner. Some of the diamonds which have a slight milky hue, when cut so as to allow the play of light within the stone, present a very beautiful appearance. The varied flashes of colored rays, in contrast with the duller hues of the stone, appear like the charming effects of the finest specimens of Siberian adularia, and are therefore entitled to the name of aventurine diamonds.
The asterism, or star-like form of six rays, which is so beautifully displayed by the sapphire when it assumes a certain form of internal arrangement of crystallization, is sometimes, though very rarely, witnessed in the diamond. There is one of this description to be seen in the Museum of the Jardin des Plantes in Paris.
The diamond is rarely found of a perfect shade of blue; but there are now in Europe several magnificent gems of this description. Foremost of all of them stood the famous blue diamond of 67²⁄₁₆ karats, belonging to the French crown. This marvel of Nature’s work, with two other diamonds of paler hue and lesser weight,—thirty-one and ten karats respectively,—disappeared on that fatal night of September, 1792, and have never since been discovered. At the present day, the finest known is that which belongs to the princely collection of the late Mr. Hope, and weighs 44¹⁄₄ karats. It is of a fine blue; but exhibits that steel-like tint which is so often seen in sapphires. The next in value and beauty is that which is preserved at Munich. It is a magnificent gem of thirty-six karats weight, and of superb color.
The crystallized black diamond is a very rare stone; and, when polished, it forms a unique gem, since it exhibits a remarkable brilliancy, proceeding, as it were, from darkness itself. We do not now refer to the compact variety, known as carbon or carbonado, which is never found except in the amorphous form, but the crystalline variety, which is of greater density and more homogeneous. The famous collector, Dogni, possessed a very fine specimen of this kind which had been cut with small facets, and exhibited a vivid eclat. It afterwards came into the possession of Mr. Bapst, who disposed of it to Louis XVIII. for the sum of twenty-four thousand francs. A large and unique diamond, almost black, formerly belonged to the late Duke of York. Several of the European mineralogical cabinets have interesting and valuable collections of colored diamonds; but the finest is to be seen in the Imperial Cabinet of Minerals at Vienna. This beautiful and complete series, which illustrates the great range of the color-suite of the gem, was the life-long labor of a Tyrolese gentleman, by the name of Helmreicher. This enthusiastic amateur went to Brazil, and passed most of his life in the mines, searching for the gems.
We will not fatigue our readers with long quotations of authors and philosophers concerning the spiritual properties of this gem; but we will briefly say, that a well-selected compilation of all these views and speculations, extending back to very early times, would form a chapter by itself, and quite as interesting as absurd. Even the good sense of the Latin philosopher Pliny was affected so far as to indulge in the belief that the gem was not only an antidote to poison, but also freed the mind from vain fears. Late in mediæval times, the adamas was invested with supernatural powers, and regarded as a spiritual creation. And even in the commencement of the seventeenth century Boetius de Boot, in his treatise on gems, asserts that the diamond possesses wonderful metaphysical properties; but remarks that they do not reside in the stone per se, but belong to the angelic spirits whom it has pleased the Almighty to connect, in a mysterious manner, with certain substances in nature.
CHAPTER VI.
THE TURKISH CASKET AND ANCIENT GEMS.
The Sultan of Turkey is said to possess many wonderful diamonds and other gems among the regalia and ornaments treasured up in the strongholds of the Seraglio; but very little is known, definitely and positively, concerning them.