Prof. Tennant — South African Diamonds. 



of diamond-cutting. The Baroness Burdett-Coutts has supplemented 

 this by the addition of money prizes, and has offered to contribute 

 the further sum of £50 for prizes in the year 1876. 



It is estimated that the value of the diamonds found at the Cape 

 from March, 1867, to the present time, exceeds twelve millions 

 of pounds sterling. 



I am enabled to exhibit not only a large collection of these 

 diamonds, but also samples of the natural materials found associated 

 with them. 1 In November, 1873, one of my former students brought 

 me the specimen from South Africa represented in Fig. 1, which in 

 its original state weighed 112 carats ; it has since been cut by a 

 London firm of diamond-cutters into the beautiful brilliant repre- 

 sented by Figs 2, 3, and 4, weighing 66 carats. The stone has a 

 delicate yellow tinge, and exceeds in size and brilliancy any diamond 

 in the British Crown. 



Fig. 1. 



Fig. 2, Front View. Fig. 3, Side View. Fig. 4, Back View. 



Fig. 1.— Natural Crystal of a Diamond recently found in South Africa. 



Figs. 2-4.— Three views of the same stone after having been cut as a brilliant by a London 



diamond-cutter. 



It may be remarked, with regard to this class of gem-cutting, 

 that 200 years since the English diamond- cutters were the most 

 celebrated in the world. The diamond-cutting trade is now 

 coming back to England, and the stone figured above affords a fair 

 sample of what excellent work can now be done here. I may 

 mention that the stone in its present form is worth £10,000, 

 whilst the value of the models of it, which have been cut by the best 

 lapidaries, is a mere trifle, that in glass costing but 10s., and that 

 in crystal but £2. The rule given by Jeffries and the best autho- 

 rities upon diamonds for ascertaining the value of cut diamonds, is 

 to multiply the square of the weight in carats by eight, and call 

 it pounds, so that this diamond would, according to this computation, 

 be worth 66 x 66 x 8 = £34,848. 



1 Prof. Tennant exhibited a South African diamond in the matrix (consisting 

 chiefly of broken fragments of chloritic and clay-slates), likewise some interesting 

 photographs of the Diamond-workings in South Africa. 



