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| Gemological information for Sapphire
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| Color | All colors
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| Crystal structure | Trigonal
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| Refractive index | 1.544-1.553
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| Durability | Very durable
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| Hardness | 7
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| Treatments | May be irradiated and heat treated, depending on variety
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| Country of origin | Worldwide deposits
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| Quartz care
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| Ultrasonic cleaning | Usually safe
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| Steam cleaning | Usually safe
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| Warm soapy water | Safe
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| Chemical attack | Avoid
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| Light sensitivity | May fade
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| Heat sensitivity | May change color
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Online G&G articles on quartz
- Winter 1939, Quartz, by Braggs, p. 58, 1p.
- Fall 1949, Aventurine Quartz, by Webster, p. 208, 4pp.
- Winter 1949, Amethyst color induced in rock crystal via cyclotron, p. 255, 1p.
- Fall 1950, Quartz from Montezuma, Brazil, turns green upon heating, p. 346, 1p.
- Winter 1950, Synthesis of Quartz Crystals, p. 359, 3pp.
- Spring 1952, The Synthesis of Quartz, p. 151, 3pp.
- Winter 1954, X-ray study of fibrous chalcedony (iridescent agate), p. 106, 3pp.
- Fall 1957, "Green" Amethyst From Four Peaks, Arizona, by Sinkankas, p. 88, 8pp.
- Summer 1960, A citrine triplet, p. 62, 1p.
- Spring 1961, Worm-like inclusions, that grow, in chalcedony, p. 151, 1p.
- Summer 1962, Quartz triplets (showing absorption spectrum), p. 307, 2pp.
- Summer 1963, Quartz cat's-eyes, p. 43, 1p.
- Winter 1963, A very rare star amethyst, p. 101, 2pp.
- Summer 1964, Reported excellent chrysoprase of Australia proves to be dyed chalcedony, p. 180, 1p.
- Fall 1964, Reported excellent chrysoprase of Australia proves to be dyed chalcedony-nomenclature, p. 216, 1p.
- Fall 1965, Marlborough Creek Chrysoprase of Australia, p. 323, 9pp.
- Winter 1966, Dyed moss in agate, p. 118, 2pp.
- Summer 1968, A 6-rayed star quartz cabochon with cat's-eye on one side, p. 313, 2pp.
- Summer 1968, Aventurine quartz inclusion, p. 315, 1p.
- Fall 1968, Spherulitic inclusions in chalcedony, p. 344, 2pp.
- Winter 1969, "Chrome chrysoprase"-jadeite-like, p. 121, 2pp.
- Winter 1969, Synthetic smoky quartz, blue quartz, and green quartz from Russia, p. 129, 3pp.
- Spring 1970, Chrome aventurine quartz (showing absorption spectrum), p. 158, 1p.
- Summer 1970, White star quartz, p. 194, 2pp.
- Summer 1971, Inclusions in amethyst that look like space capsules, p. 322, 2pp.
- Fall 1971, Dyed chalcedony-excellent jade imitation (showing absorption spectrum), p. 350, 1p.
- Spring 1972, Synthetic quartz from Ohio, p. 8, 2pp.
- Summer 1972, A 20-inch high carved rock crystal vase, p. 43, 1p.
- Fall 1972, An odd 6-rayed star quartz, p. 89, 2pp.
- Spring 1973, Moveable bubbles in quartz crystals, p. 150, 2pp.
- Summer 1973, Fire agate, p. 177, 1p.
- Summer 1973, Petrified palm root, p. 182, 2pp.
- Fall 1973, Fade test on Gamma-irradiated quartz, p. 212, 2pp.
- Winter 1973, A rock crystal brilliant with tourmaline needle crystal running from culet to center of table, creates many reflections, p. 235, 2pp.
- Winter 1973, Greenish-yellow citrine, gamma-irradiated (test available), p. 236, 2pp.
- Spring 1976, Jade-like quartz, p. 155, 2pp.
- Winter 1977, Imitation bloodstone, p. 234, 1p.
- Winter 1977, Star Quartz and Banded Synthetic Quartz, p. 310, 3pp.
- Winter 1977, Another Multi-Star Quartz, p. 364, 2pp.
- Winter 1977, Synthetic Amethyst from Russia, p. 365, 2pp.
- Spring 1978, Inclusions in Agate and Their Origins and Significance, By Roger K. Pabian, p. 16, 12pp.
- Winter 1978, Star Quartz, p. 364, 2pp.
- Winter 1978, Synthetic Amethyst, p. 365, 2pp.
- Spring 1979, Fire Agates of Deer Creek, Arizona, by James L. Sweaney, p. 130, 13pp.
- Spring 1979, Synthetic Amethyst, currently no test for a flawless amethyst, p. 151, 3pp.
- Summer 1979, Quartz: Myth and Magic, Science and Sales, by Cheri Lesh, p. 174, 5pp.
- Summer 1980, Citrine-Amethyst Quartz - A Gemologically New Material, by John I. Koivula, p. 290, 4pp.
- Winter 1980, More News On Citrine-Amethyst Quartz, by John I. Koivula, p. 409, 1p.
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