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Ch. 1: Properties and Characteristics Gemstones

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THE PROPERTIES AND CHARACTERISTICS OF PRECIOUS STONES.
Hardness.
Y the term hardness, must not be under, stood the ordinary acceptation of the word, "difficulty of breakage," but the scientific definition, namely, the resist-ance one body offers to the mechanical pressure of an-other, or, in other words, liability or non-liability to scratch. In the Table A. it will be seen that on the one side is given the mineralogical scale of hardness of Moh, the German author, who has taken ten different substances as standards of various degrees, and classed them in numbers from one to ten ; ten being the dia­mond, as the hardest-known body. On the other side, the substances which scratch one another are indi-cated, and as glass and quartz, or rock-crystal, are easily procured, and most precious stones are of equal
Emanuel: Diamonds and Precious Stones Page of 295 Ch. 1: Properties and Characteristics Gemstones
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