Stones and minerals that are sufficiently beautiful, durable, and rare are known as gemstones.A gemstone with only one of these qualities is less desirable than one with all three. For example, a stone with rich color but not sufficiently durable to withstand daily wear in rings finds little favor as a gemstone except in brooches or pins where the stone is relatively safe from abrasion. Likewise, a stone that is beautiful and durable may be of little interest as a gemstone because it is commonly found in great quantities. To be valued highly, gemstones must be beautiful to the eye, durable enough to withstand wear, and rare enough so that they are not easily obtained.
King, E. A., Jr., 1961, Texas Gemstones: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 42, 42 p.
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The University of Texas at Austin, Bureau of Economic Geology
Report of Investigation