The Prismatic Corundum found among the Tors Hills near Rajmahal, on the Bunas, in irregular rolled pieces, small, and of a light green colour, are sold as emeralds by the natives, under the name of panna or pans.
Beryl includes the emerald of jewellers, and also their aqua marine. It is an alumino-glucinium silicate, the aluminium being in the emerald apparently displaced to a minute ' amount by chromium.
Aqua marine includes clear beryls of a sea-green or pale-bluish or bluish-green tint. Hindus and Muhanunadans them pierced as pend ants and in armlets. They are the suing or seigu of the Burmese and the zamarrud of the Persians. At the Madras Exhibition of 1855, a good specimen of aqua marine was contributed from Mysore ; other samples of long reed crystals were forwarded by the Nellore Local Committee.
Topaz was so called from the island of Topazion in the Red Sea. There is a gold-coloured and greenish-yellow topaz. Oriental topaz is of little value in commerce. The gem is of a yellow tint, seldom deep, of a light straw colour. Oriental topaz, ruby, and sapphire consist of 90 per cent. of pure alumina, 7 per cent. of silica coloured with oxide of iron.
Zircon consists of zirconic and silicic dioxides. Its pellucid varieties are gems. The dull green is the jargoon ; the red-tinted varieties are the hyacinth or jacinth. The yellow and blue tints are rare, but the more pellucid and colourless zircon, from its exceptionally high refractive power, approaches even the diamond in brilliancy. Zircon is found in the Ceylon districts of Matura, and Saffragam. Matura diamond is the name applied to its finest varieties by the dealers in gems. Besides the two well-established species, common zircon and hyacinth, there is a third, massive, opaque, and uncrystallized, and of a dark brown colour. Specimens of it from Saffragam weigh two or three ounces. The yellow varieties are sold by the natives as a peculiar kind of topaz, the green as tourmalines, the hyacinth red as inferior rubies, and the very light grey as im perfect diamonds. All the varieties are found in the beds of rivers or in alluvial ground, which, both in Saffragam and Matura, is of the same kind. Zircon occurs in alluvium in the Ellore district of the Madras Presidency.
Chrysoberyl consists of glucina and alumina (aluminate of glucinum). As a gem it is known as the oriental chrysolite, also as cymophane. It is a beautiful greenish-yellow stone, almost equal in lustre and hardness to the sapphire. Chrysoberyl is sometimes with a yellow or brownish tinge, and occasionally presenting internally an opalescent bluish-white light. When green, transparent, and
free from flaws, it is much prized. The less trans parent specimens, when cut en cabochon, furnish one of the kinds of precious stones to which jewellers give the name of cat's eye. The dark green variety from the Aral is called Alexandrite.
Diamonds are found in India, Sumatra, Borneo ? Australia, the Cape Colony, the Aral mountains, Brazil, and South America. It occurs in India, in the Dekhan, near the river Pennar in the Cuddapah district., and near Banaganapilly, in the lower part of the Kistna, formerly near Ellore, and bed of the Godavery. The diamond sold in 1856 ? to the emperor Louis Napoleon for £5000, was said to have been obtained in the Pennar or at Banaganapilly. They are also found at Palma in Bundelkhand, and at Sumbulpore on the Mahanadi. Thara and 'fora are two diamond-washing tribes who possessed sixteen jaghir villages at Sumbul pore. They are supposed to be of African origin. Another aboriginal tribe called the Jiiira are said to have held their villages rent-free on condition of washing the sands of the river for diamonds, which were made over to the raja, while the gold ob tabled at the same time remained the perquisite of the finders.
Diamonds are found in quartz conglomerates containing oxide of iron, also in alluvium, in loose and embedded crystals, almost always of small size, and most frequent in company with grains of gold and platinum. Diamonds are found crystalline and amorphous, and of all colours, white, yellow, orange, red, pink, brown, green, blue, black, and opalescent. The rocks in which the diamond occurs in Brazil are either a ferruginous quartzose conglomerate, or a lamin ated granular quartz called itacolumite. The latter rock occurs in the Arals, and diamonds have been found in it ; and it is also abundant in Georgia and North Carolina. In India, the rock is a quartzose conglomerate. Mr. Ball tells us that there are diamond mines in various parts of Bundclkhand, but the principal are near Panna, its capital. Other diamond areas are at Badra chellum on the Godavery, near the Kistna river, and near Banaganapilly and Cuddapah. A diamond tract occupies a considerable area between the Mahanadi and Godavery rivers,viz. at Sumbulpore, with the bed of the 31alianadi for many miles above it, and Weirag,arh 80 miles to the S.E. of Nagpur. About A.D. 1870, some small diamonds were stated to have been found in a bill stream near Simla.