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Gem and Ornamental

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Figure 9.22Coated p hk bead with worn surface.TesaUllravioM light. Pearls from marine oysters fluoreace a ch&-white under W light, while some frebwater pearls fluoresce ayellowish colour. However, coated plastic pearls can also fluoresces yellow colour. As shell - <strong>and</strong> therefore shell bed^ - have the samefluorescence as marine pesrls, the test is not concluive.There is an old test for pearls that involves rubbing them gentlyamss the teeth. It is not a desmctive test, but it is unhygienic.

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