[Extracted from the Geological Magazine, Decade II., Vol. IL, 

 No. 11, November, 1875.] 



Notes on Diamonds from the Cape of Good Hope. 1 

 By Professor Tennant, F.G.S. 



rpHE first South African diamond was found in March, 1867, and on 

 J_ examining its physical characters, it was pronounced by Dr. 

 Atherstone to be genuine. When this stone was received in London, 

 it created considerable interest, and also some degree of suspicion, 

 some persons having asserted that it was brought forward for mer- 

 cenary purposes ; letters even appeared in the public papers implying 

 that it was impossible it could have been found near Hope Town. 

 As Dr. W. G-. Atherstone, F.G.S., of Graham's Town (who in March, 

 1867, examined and pronounced the stone to be a diamond), is now in 

 Bristol, I beg to offer a few general remarks on the Cape diamonds, 

 and also to express in public my thanks to him. 



The late Mr. Mawe, who wrote on diamonds, and described their 

 mode of occurrence in his Travels in Brazil (London, 1812), often 

 expressed to me his opinion of the probability of their existence in 

 South Africa, and said that if people only knew them in the natural 

 state he felt confident they would be found. 2 He died in 1829, and 

 I took every opportunity to make the subject known by means of 

 short papers, accompanied by figures showing the ordinary crystal- 

 line form of the diamond. 



The number and quality of diamonds from the Cape are equal to 

 those from the Brazils, which have chiefly supplied Europe during 

 the last eighty years. 



About ten per cent, of the Cape diamonds may be classified as 

 of the first quality, fifteen per cent, of the second, twenty per cent. 

 of the third ; the remainder, under the name of bort, are employed 

 for cutting diamonds, and for the various economic purposes to which 

 this valuable substance is applied by the glazier, the engineer for 

 drilling rocks, the lapidary, and others. Many diamonds contain 

 specs and cavities ; these are placed in the hands of skilled workmen 

 who are acquainted with the cleavage, and by careful manipulation 

 they are frequently able to remove these blemishes, and so to obtain 

 portions of the gems of the first quality for making small " bril- 

 liants," "roses," and "tables." 



The cutting and polishing of diamonds was carried on in London 

 with great success 200 years ago ; subsequently it was carried on 

 chiefly in Holland ; but several attempts have been made to re-estab- 

 lish the trade in this country. 



In 1874 the Turners' Company offered prizes, in the form of 

 medals and the freedom of the City of London, for the best specimens 



1 Read before the Geological Section of the British Association at Bristol, Sep- 

 tember 1st, 1875. 



2 Prof. Tennant explained that the diamond in its natural state bore considerable 

 resemblance to a piece of gum. 



