Scratch testing (or hardness testing) is one of the most destructive gemstone tests. Never perform a scratch test on a finished stone. This can fracture or shatter the gem, even if tested on an inconspicuous area.
Gem rough can be scratch tested, but caution is needed. Keep in mind that the rough may have incipient fractures that can’t be seen or internal stress that will open up easily to pressure. For these reasons, …
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