The range of colour in diamonds is rather extensive. They occur in various tints, which include green. black, blue, red, pink, and yellow. Black diamonds hail from Borneo. They are extremely rare, have much brilliance, and are so hard that they can only be polished with their own dust, as the ordinary diamond dust makes no impression on their surface. The Duke of Richmond owns one big black diamond which for centuries did duty as the eye of an Indian idol; and a famous black diamond was owned by a former Duke of Wellington.
The Hon. Mrs. Ronald Greville has some black diamonds; and a necklace of these stones, said to be the only one in the world, belongs or belonged to Mrs. Celia Wallace, a well-known American. This was composed of fourteen pendants of black diamonds of great brilliance, which were hung on a chain made of platinum. Black diamonds
Photo, Bolak l601 Dress were once the mourning jewel of the Russian Court, and are much liked by Russian aristocrats. By the way, it is an accepted fact that the Russian ladies prefer coloured stones to pearls or ordinary diamonds. They, of course, have these latter, but they more often wear their emeralds, rubies, and sapphires, which are of great beauty and immense value.
Red diamonds are extremely rare, but one is said to have been sold by Mr. Streeter for £800 which is now among the Crown jewels of Russia. Blue and green diamonds are also scarce; pink and violet come next, and then orange and canary colour. Yellow diamonds have but small value. A pale green diamond is preserved in the vaults at Dresden, and is sometimes worn by the King of Saxony. The Duke of Brunswick had among his priceless collection of gems a pink brilliant of immense value which had belonged to an Indian potentate. The famous sapphire blue brilliant known as the Hope diamond is one of the. most valuable coloured stones now in existence. This weighs 44 3/8 carats, and has changed hands at £ 80,000.
The Countess of Crawford has marvellous coloured diamonds in the form of brooches, each of which is said to be worth many thousands; and Lady Margaret Campbell owns and wears a comb of blue, pink, and black diamonds, which was given her when she married by her brother-in-law, the Marquis of Breadalbane. Lady Beatrice Herbert has a wondrous necklace which was a present from his Highness Aga Khan at the time of her marriage. This jewel is composed of countless stones set in the finest goldwork, and among them are red, green, blue, and black diamonds of great size and beauty.
In buying precious stones much caution is required. Few wares are more liable to faults and frauds; also other stones of a like nature are used in place of the real article. For instance, white sapphires and white topazes are often passed off as diamonds by dishonest dealers.
Hardness is the best test that a diamond is genuine. If the stone in question cannot be scratched by a ruby or a sapphire it can only be a real diamond. The simplest way to test a diamond is as follows: Rub the stone on a bit of common glass, and if it scratches or rips the glass, it is a real diamond, but a false one if it makes no impression. The best sham diamonds are made of crystal backed with foil, and the cheaper sorts from glass prepared in the same manner.
Diamonds were known to the ancients, and to make these stones was the dream of the old-time alchemists. This dream is said to have been realised by the French chemist, Monsieur Henri Moisseau. But the largest stone he makes is, as yet, most minute in size and by no means perfect.
Diamond-cutting has become a science, and the best diamond-cutters in the world are said to be found at Amsterdam. But diamond-cutting is also carried on with success at Antwerp and in London. The stone is cut in three ways-brilliant -cut, table-cut, and rose-cut; but rose diamonds are not liked by everyone, and become every day of less value. The process is, however, quite different to what it was a decade or so ago. Diamonds are now cut with many more facets, which gives a greatly increased brilliance. A visit to one of the best diamond-cutting factories in Amsterdam makes a most interesting experience. The first process is that of splitting or cleaving the rough stones. In this, a sharp diamond edge is used to cut a nick or groove in the stone, after which a wedge-shaped steel knife is placed in the nick, and hit a hard blow with a steel hammer. If the nick has been properly placed, all will go well, and the stone divides into two pieces; but if an error has been made, it may cause the stone to break up irregularly, and perhaps lead to the loss of thousands of pounds.
The next process is that of cutting, in which the split pieces are roughly formed into the shape of a brilliant by being rubbed against other diamonds. Then comes the work of sawing, which consists of dividing the stone by means of a thin disc of steel or phosphor copper that revolves some 3,000 times a minute. The last important process is that of grinding the 58 facets possessed by a brilliant, and giving them the final polish. For this purpose, use is made of a horizontal wheel, composed of a peculiar quality of iron, and covered with a mixture of diamond dust and oil, and which is turned at a speed of about 2,400 rotations a minute. The final stage of polishing is performed on a mill of the same kind, but with a smoother face, which after a while gives the final perfection of polish. Electricity is used both for lighting and for driving all the machinery. Many charming fancies are connected with the diamond. Tradition claims for it protective qualities. Napoleon had a diamond set in the hilt of his sword with the idea of safety and victory; and Ruthven gave Mary Queen of Scots a diamond ring as a protection against her enemies.