110 DIAMOND, 



at a temperature of 14° Wedgwood, and is 

 wholly consumed, producing carbonic acid 

 gas ; also combustible in oxygen gas and in 

 the oxyhydrogen flame, and in the electric 

 arc is converted into coke and graphite. 



The Diamond has in all ages been held 

 in the highest estimation. 



The most valuable are perfectly colonrless. 

 There is rarely more than one tinge of colour 

 in the same stone, but, while it is consider- 

 ably deteriorated by a dull or faint tint, its 

 commercial value, on the other hand, is 

 greatly enhanced by a well-defined tint of 

 pink, green, or blue. 



Diamonds are weighed in carats (151^ of 

 which make one ounce troy) of o*16 or oj 

 grains each. The medium value of a Dia- 

 mond, when rough, is £2, and the value of 

 rough Diamonds of greater weight is esti- 

 mated by multiplying the square of their 

 weight in carats by 2, which gives the value 

 in pounds. Example : — To find the value 

 of a rough Diamond 2 carats in weight. The 

 square of the weight 2x2 — 4, this multi- 

 plied by 2 = 4x2 = £8, the value of a Dia- 

 mond of two carats. 



The price of polished Diamonds is much 

 greater, for, amongst other reasons, the pro- 

 cess of polishing is so uncertain, that the 

 cutters think themselves fortunate in retain- 

 ing one half the original weight, and the 

 greater number of the Diamonds found are 

 very small in size, their rarity increasing at 

 a rapid rate in proportion to their weight. 

 The average weight and size of Diamonds 

 may be learned from the results of an exa- 

 mination of 1000 stones by Professor Ten- 

 nant, who found that, out of the entire 

 number, one half weighed less than half a 

 carat, 300 less than 1 carat. 80 Aveighed 1^ 

 carats, 119 varied from 2 to 20 carats, and 

 1 weighed 24 carats. 



A polished Diamond, of the purest water, 

 well cut, and free from flaws, is worth £8 •, 

 above that weight the value is calculated by 

 multiplying the square of the weight in 

 carats by 8. Thus: the value of a polished 

 Diamond of 2 carats = 2 x 2 x 8 = £32 : the 

 value of a polished stone of 3 carats 3 x 3 x 

 8 = £72, and so on. 



Above 10 carats the price increases in 

 such a rapid ratio, that few persons can 

 afford to purchase the larger stones, and it 

 therefore becomes difficult to sell them at 

 their calculated value. 



The natural cleavage is taken advantage 

 of by the native jewellers in the East, who 

 form table Diamonds by adroitly striking the 

 stone placed between two sharp-edged tools. 



The art of cutting and polishing Diamonds 



DIAMOND. 



was discovered by Louis van Berquen, a 

 citizen of Bruges, in 1456, previously to 

 which time the Diamond was only known 

 in its rough, or in its cleaved state. 



The cutting is effected (chiefly by Jews 

 at Amsterdam), by means of a' scharf or 

 mill, consisting of an iron wheel about 10 

 inches in diameter, which is made to re- 

 volve horizontally with great rapidity, from' 

 2000 to 3000 times in a minute. The stone, 

 imbedded in pewter at one end of an arm, is 

 pressed on the wheel, smeared with diamond- 

 dust and oil, by means of weights varying 

 from 2 to 80 lbs., and regulated according to 

 the amount of pressure it may be considered 

 necessary to produce. 



The ancients did not possess the art of 

 pohshing the Diamond, but its extreme 

 hardness, and the regularity of its form, 

 coupled with its rarit}- and supposed inde- 

 structibility, car.sed them to attach a high 

 value to it, and to endue it with many sup- 

 posed virtues. 



Although Diamonds do not appear to have 

 been so much in request with the Romans 

 as pearls, the former are, nevertheless, de- 

 scribed by Pliny as amongst the most valua- 

 ble of human possessions. 



From its extreme hardness, which was be- 

 lieved to be sutficient to shiver both the ham- 

 mer with which it was struck, as well as the 

 anvil on Avhich it was placed, and the impossi- 

 bility of rendering it red hot by the most vio- 

 lent heat, it was called «5a.,tt«?, (or unconquer- 

 able ), b}' the Greeks, a name which has been 

 adopted by the moderns, though applied in- 

 differently to the loadstone as well as the 

 Diamond. It was also imagined to destroy 

 the effect of poisons, and to cure insanity. 



In the East it is still supposed by the 

 credulous to act as a preservative against 

 lightning, and to cause the teeth to fall out 

 when placed in the mouth; but the last bad 

 quality has been disputed by one author, 

 who supports his objection (Avith some show 

 of reason), by stating that diamond -powder 

 has been used as a dentifrice without pro- 

 ducing such injurious effects upon the teeth. 



Owing to the general resemblance be- 

 tween Kock Crystal and Diamond, the 

 former is called in the East kacha, or unripe, 

 and the latter joaMa, or ripe Diamond. 



In addition to its value as a precious stone, 

 the Diamond is employed for engraving and 

 cutting glass, in splinters for drilling, and, 

 reduced to powiter, for polishing and cutting 

 other gems. Diamond-powder, being worth 

 £50 per ounce, is too expensive to be used 

 alone ; and it is, therefore, generally mixed 

 with emery, and applied to the mill with 



