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<p>[QUOTE=&quot;Bronwen, post: 810363, member: 5833&quot;]I know about the hot needle test for some kinds of materials, but what did you mean by this?&nbsp; What did you do?&nbsp; Glass will craze or shatter if you get it hot, then plunge into cold water, perhaps some soft stones you would never use in jewellery, such as sulfur, would too, but there is a wide range of minerals used in jewellery that would not be vulnerable to this.</p><p><br /></p><p>&#039;Hardness&#039; in the mineral world is defined by what can scratch what.&nbsp; Diamond can scratch any other stone.&nbsp; If you gave a diamond a good whack with a chunk of jade, it would crack/shatter.[/QUOTE]</p><p><br /></p>

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