22 DIAMOND GENUS. Befides thefe two colours, it occurs blue, reef, brown, yellow, and green. Of the blue the only variety which Werner pof- fefles is indigo blue : it probably pafles into red. Of red it occurs rofe red and cherry red ; from the latter it pafles into clove brown and yellowilh brown", from this into ochre yellow, wine yellow, lemon and fulphur yellow: further into filkin green, afparagus green, piftachio green, leek green, and laftly into mountain green : which latter probably pafles into greenifh grey. The clove brown fometimes approaches to black, "lhe indigo blue and the red are the rareft varie ties, The fnow white is the mod highly valued, and the grey, and Hill more the brown, are the lealt valued. The colours are mod generally pale and light, fel- dom deep, and far feldomer dark. It exhibits a molt beautiful play of colours. It occurs in indeterminately angular and complete-, ly fpherical grains, which fometimes prefent planes of cryflaliization : it alfo occurs cryltaliized. Its fundamental cryltal is the octaedron, which palfes on the one fide, ill, Into the fimple three-fided pyramid, with truncated angles, and probably alfo into the fix fided table, in which the terminal planes ^are fet alter nately oblicpue and Itraight on the lateral planes. 2d, On the other fide it divides itfelf into three branches. a, Octaedron/