- gemstones' beauty, durability, and rarity
- the noncrystalline materials of organic origin that are gemstones: amber, pearl, red coral
- rubies, sapphires, and emeralds are synthetic gems
- only 16 minerals have achieved importance: beryl, chrysoberyl, corundum, diamond, feldspar, garnet, jade, lazurite, olivine, opal, quartz, spinel, topaz, tourmaline, turquoise, and zircon
- diamonds for jewelry are graded on the basis of color from blue-white to yellow; grading is also done for purity which varies from perfectly clear and pure to those with many impurities and flaws
- pearls' color varies according to the waters from which they come: Persian Gulf cream-colored, Australia white with bluish shades, pink from Sri Lanka, etc.
- ivory comes from the tusks of the elephant, hippo, warthog, walrus, sperm whale, narwhal - and extinct mammoth (fossil ivory)
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