History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c36.s7.7
History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c36.s7.7
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c36.s7.7
2 *Hardness* :—The spurious substitute of any precious stone may easily be detected by its difference in hardness and low specific gravity. The suspected gem may also be rubbed on a whetstone; if it simply gains in lustre but does not lose in weight (by abrasion), the specimen is to be regarded as genuine (test of a ruby). Diamond and corundum alone will scratch ruby and sapphire. All the gems occurring in this world, as also the metals, will be scratched by a diamond, but the latter will not be similarly affected by the former. A diamond alone will scratch a diamond.