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Rh to make trial with three or four Emralds, whoe being true was not doubted, and found them all omewhat, though not equally, endow'd with Electricity, which I found to be yet more coniderable in an Emrald of my own, whoe colour was o excellent, that by skilful perons 'twas look'd on as a rarity. And though, by this ucces of my inquiry, I perceived I could not, as ele I might have done, hew the Curious a new way of judging of true and fale Emralds, yet the like way may be, though not always certain, yet oftentimes of ue, in the etimating whether Diamonds be true or counterfeit, epecially, if, being et in Rings, the ureft way of trying them cannot conveniently be employed. For whereas Glas, though it have ome Electricity, eems, as far as I have oberved, to have but a faint one, there are often found Diamonds that have a very vigorous one. And I do not remember I met with any Electrick of the ame bulk, that was more vigorous than a rough Diamond I have, which is the ame that I formerly mentioned to have moved a Needle above three minutes after I had ceaed to chafe it. And this brings into my mind, that it has been oberved, that Diamonds draw better whilt rough, than they do after they are cut and polih'd,