1848.] The Nizam's Diamond. 153 



I have had now exact models cast in glass from the leaden one ex- 

 hibited at the meeting, and I find that 



Grains. 



Their absolute weight is, , 1 164.50. 



Their Specific Gravity, , . 3.70. 



Now according to various authorities we have for the specific gravity 

 of the Diamond 



Ure, • 3.53. 



Brewster, colourless, 3.52. 



orange, , 3 55. 



Jameson twelve authorities, mean, 3.52. 



Mean, 3.52. 



And hence assuming our model to be exact, (and it is very nearly so,) 

 we have by a simple proportion not quite 1108 grains for the actual 

 weight of the Nizam's diamond. 



This is equal to 277 Carats of weight of the rough diamond, and as 

 the rough stones are usually taken to give but one half of their weight 

 when cut and polished, it would allow 138|- Carats, or a weight between 

 the Pitt (or Regent) diamond (136f Carats), and that of the Grand 

 Duke of Tuscany (139 Carats), for it in its present condition ; and if 

 we take it that one-eighth of what it would be when polished was taken 

 off with the splinter sold to the native, as related by Captain Fitz- 

 gerald, we shall then have 155f Carats for the possible weight of it, if 

 it had been cut and polished entire ; which would then place it as to 

 weight between the Tuscan and the great Russian Diamond of 195 

 Carats, which last is well known to be an Indian stone. 



We are not informed if this stone is considered as likely to be one of 

 pure water, which can only be ascertained by polishing it, though we 

 know that the natives of India, and particularly of the Deccan, are too 

 good judges of diamonds to mistake a topaz for one, and it is stated that 

 70,000 Rs. have been paid for the fragment. It therefore certainly 

 adds one extraordinary fact more to the history of this most wonderful 

 of the gems." 



