to make trial with three or four Emralds, 

 whofe being true was not doubted, and 

 found them all fomewhat, though not e- 

 qually, endow'd with Eledtricity, which I 

 found to be yet more confiderable in an 

 Emrald of my own, whofe colour was fo 

 excellent, that by skilful pcrfons 'twas 

 look'd on as a rarity. And though, by this 

 fucceft of my inquiry, I perceived I could 

 not, as elfe I might have done, (hew the 

 Curious a new way of judging of true and 

 falfe Emralds, yet the like way may be, 

 though not always certain, yet oftentimes 

 of ufe, in the eftimating whether Dia- 

 monds be true or counterfeit, efpecially, 

 if, being fet in Rings, the fureft way of 

 trying them cannot conveniently be em* 

 ployed. For whereas Glafs, though it 

 have fomc Ele#riciiy, feems, as far as I 

 have obferved, to have but a faint one, 

 there are often found Diamonds that have 

 a very vigorous one. And I do not re- 

 member i met with any Ele&rick of the 

 fame bulk* that was more vigorous than 

 a rough Diamond I have , which is the 

 fame that I formerly mentioned to have 

 moved a Needle above three minutes af- 

 ter I had ceafed to chafe it. And this 

 brings into my mind, that it has been ob- 

 ferved, that Diamonds draw better whilft 

 rough, than they do after they are cut and 



polifh'd, 



