Much artistic skill is requisite in diamond cutting, in order to retain the gem of as great bulk as possible.
A diamond known as the Moghul was cut for Shah Jahan by Hortensio Borgio, a It weighed 793,i carats, and he reduced it to 186 carats, which angered the emperor so that he fined him Rs. 10,000, in fact all his possessions.
The Koh-i-Nur weighed on arriving in London carats, and was valued at £140,000. It was cut by Herr Voorsanger, under Messrs. Coster of Amsterdam, in time atelier of the crown jewels in London, and it was reduced to and is valued at £100,000. It is the personal property of the Queen-Empress Victoria. Mr. Streeter is of opinion that it is the Moghul diamond. The Regent diamond, before cutting, weighed 410 carats, and 1361 after it was cut.
It is supposed that the Rhodes diamond would, when cut, weigh 100 carats. In July 1853, a diamond was found in Brazil which weighed 251 carats, but was rednced in cutting to 125.
mr. Bryce Wright, of 204 Regent Street, is In pouts Rion of a diamond of seine note, sot in a ring which was kept for navy years in tho treasury of the Idoghul emperors of Hindustan. It is one of the very few ) known diamonds that are cut or engraved, and it Is supposed that the work upon it, owing to the extreme hardness of the stone, must have cost years of incessant labour. The engraving is believed to be by a Persian artist ; it is a monogram composed of two Arabic words interlocked together, making up the invocation, ' 0 Ali.' The date of the work is supposed to be A.D, 1200.
All the diamond localities yield atones which mineral ogically are true diamonds, but do not possess the high qualities to entitle them to be regarded as precious stones. And this remark is equally applicable to all the varieties of the corundum, felspathic, and other minerals which furnish the gems of the jewellers.
Emeralds are inentiene 1 in Exodus xxviii. 18, also in ,Tobit, Judith, Ecclesiastes. and Ezekiel. The emerald mines in Jabl Zabarah in Egypt—the Smaragdus mons of the ancients—were worked n.e. 1650, in the time of Sesostris n. These mines (Bunsen's Egypt, ii. 303)
were on the Kosseir Road, from Koptos to Acnnum (Philoteras).
The Felspar group of minerals includes several of value in the arts, such as lahradorite, with its beautiful play of colours, moon-stone or orthoclase, valencianite, Amazonite or Amazon stone, and lazulite, called blue felspar and blue spar.
Fossil wood is in large quantity in Burma, in Sind, and at Verdachell um and Ootatoor,west of Pondicherry. It is used for ornaments.
Garnet, from which carbuncles are formed, is in great abundance in the south of India, chiefly in gneiss rock in tho Guntur and Coimbatoro districts, also at the Munzerabad Ghat, and in the Aravalli range. Amongst its varieties are the violet-tinted almandine ; the yellow and hyacinthine garnets known as cinnamon-stone and essonite, which contain calcium and aluminium ; the garnet and pyrope, or Bohemian garnet varieties, when cut en cabochon, are the carbuncle of jewellery ; but the carbuncle (e4cei) of the ancients included all gems of a red colour, such as hyacinths, rubies, garnets. Other varieties of garnet are alloehroite, topazolite, melanite, colophanite; and grossular garnet.
polite and cyanite or kyanito imitate the sapphire, but the greater hardness of the sapphire affords an easy test of its genuineness. Kyanite is a silicate of alumina, and occurs in long, thin, blade-like crystals of a clear blue or bluish-white colour.
Jade, which the Chinese so highly value, is brought from Central Asia, one locality being at Gulbagashen in tho valley of Karakash. The Yu or Jade mines of Independent Burma are in the Mogoung district, about 25 miles S.W. of Mains-Khum. Momien in Yunnan was formerly a chief seat of the manufacture of jade, and still sends out a considerable quantity of small articles. Jade was imported from Burma in 1880-81 to the value of Rs. 2,45,650, and mostly all re-exported to Singapore and China. It is also called nephrite.
Jet is imported into India from Europe, and is only worn by Europeans. Large quantities of lignite are found in the tertiary strata along the sea-coast of India, but none of it takes a good polish.