DIAMOND. 13 This rule, however, actually holds good only in the smaller diamonds of 20 carats and under; the larger ones, in consequence of the scarcity of purchasers, being disposed of at prices greatly inferior to their estimated worth. The value of some of the most perfect diamonds exceeds that given in the table ; but for a stone that is flawed, cloudy, or of a had colour, sometimes three quar ters of the whole tabular value must be deducted. 2. The transparent snow white variety is considered to be the most valuable ; the green and yellow' varieties are also much esteemed; the green and blue varieties were formerly more valu'd than at present; and the least valuable are the grey and brownish varieties. Black diamonds are much prized by collectors. 3. The principal use of the diamond is in jewellery; it is also used by lapidaries for cutting and engraving upon the hardest gems, and by clock-makers in the finer kinds of clock-work; in the glass-trade, for squaring large pieces or plates of glass, and among glaziers for cutting their glass. 4‘. Zircon is sometimes substituted for diamond, but may be distinguished from it by the muddiness of its co lours, its very feeble play of colour, inferior lustre and hardness. 5. We may here give a short account of some of the most remarkable diamonds noticed by authors. The great Brazilian diamond, in the possession of the Queen of Portugal, is the largest that has been hitherto discovered, its weight being stated at 16S0 carats. Ma ny are of opinion, that this remarkable stone is a fine white-coloured topaz ; and therefore the largest undoubt ed diamond, is that mentioned by Tavernier, which was in the possession of the (heat Mogul, and which that traveller found to weigh 279,?, carats. Its form and size are etjual to that of half a hen’s egg, and it is cut in the
