[ { "name": "Diamond", "name_ja": "ダイヤモンド", "mineral_family": "diamond", "chemical_formula": "C", "mohs_hardness": [10, 10], "refractive_index": [2.417, 2.419], "specific_gravity": [3.50, 3.53], "crystal_system": "cubic", "cleavage": "perfect, octahedral", "luster": "adamantine", "dispersion": 0.044, "colors": ["colorless", "yellow", "brown", "pink", "blue", "green", "red", "black"], "common_treatments": ["HPHT color enhancement", "irradiation", "laser drilling", "fracture filling"], "birthstone_months": [4], "zodiac_signs": ["Aries", "Taurus"], "wikidata_qid": "Q5283", "common_simulants": ["moissanite", "cubic zirconia", "white sapphire", "white topaz", "white zircon"], "notes": "Hardest natural material known. Forms under high pressure ~150km below Earth's surface. Lab-grown diamonds (HPHT and CVD processes) are gemologically identical to natural; require specialized testing to distinguish.", "sources": ["GIA Diamond Encyclopedia"] }, { "name": "Ruby", "name_ja": "ルビー", "mineral_family": "corundum", "chemical_formula": "Al2O3 (Cr impurity)", "mohs_hardness": [9, 9], "refractive_index": [1.762, 1.770], "specific_gravity": [3.97, 4.05], "crystal_system": "trigonal", "cleavage": "none (parting common)", "luster": "vitreous", "dispersion": 0.018, "colors": ["red", "pinkish-red", "purplish-red"], "common_treatments": ["heat treatment (near-universal)", "lead-glass fracture filling", "diffusion treatment"], "birthstone_months": [7], "zodiac_signs": ["Cancer", "Leo"], "wikidata_qid": "Q53393", "common_simulants": ["red garnet", "red spinel", "red tourmaline", "glass", "synthetic ruby"], "notes": "Chromium impurity gives red color. Burmese (Myanmar) 'pigeon's blood' rubies command the highest prices. Most market rubies are heat-treated; untreated stones with lab reports premium dramatically.", "sources": ["GIA Colored Stone Reports", "ICA Gemstone Standards"] }, { "name": "Sapphire", "name_ja": "サファイア", "mineral_family": "corundum", "chemical_formula": "Al2O3 (Fe, Ti impurities)", "mohs_hardness": [9, 9], "refractive_index": [1.762, 1.770], "specific_gravity": [3.97, 4.05], "crystal_system": "trigonal", "cleavage": "none", "luster": "vitreous", "dispersion": 0.018, "colors": ["blue", "yellow", "pink", "orange", "green", "purple", "colorless", "padparadscha (pink-orange)"], "common_treatments": ["heat treatment (very common)", "diffusion (Be, Ti)", "lattice diffusion"], "birthstone_months": [9], "zodiac_signs": ["Virgo", "Libra"], "wikidata_qid": "Q4118", "common_simulants": ["blue spinel", "blue topaz", "iolite", "tanzanite", "synthetic sapphire"], "notes": "Same mineral as ruby (corundum); 'sapphire' refers to any color except red. Kashmir sapphires (cornflower blue, velvety) command extreme premiums. Padparadscha is the rare pink-orange variety.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Emerald", "name_ja": "エメラルド", "mineral_family": "beryl", "chemical_formula": "Be3Al2(SiO3)6 (Cr, V impurities)", "mohs_hardness": [7.5, 8.0], "refractive_index": [1.577, 1.583], "specific_gravity": [2.68, 2.78], "crystal_system": "hexagonal", "cleavage": "imperfect, basal", "luster": "vitreous", "dispersion": 0.014, "colors": ["green to bluish-green"], "common_treatments": ["cedarwood oil (near-universal)", "polymer/resin filling", "color enhancement"], "birthstone_months": [5], "zodiac_signs": ["Taurus", "Cancer"], "wikidata_qid": "Q193260", "common_simulants": ["green garnet (tsavorite, demantoid)", "green tourmaline", "peridot", "chrome diopside", "synthetic emerald"], "notes": "Beryl colored by chromium and/or vanadium. Heavily included by nature ('jardin'); almost universally oil-filled to mask fractures. Colombian (Muzo) emeralds command the highest prices.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Aquamarine", "name_ja": "アクアマリン", "mineral_family": "beryl", "chemical_formula": "Be3Al2(SiO3)6 (Fe2+ impurity)", "mohs_hardness": [7.5, 8.0], "refractive_index": [1.567, 1.590], "specific_gravity": [2.66, 2.80], "crystal_system": "hexagonal", "cleavage": "imperfect, basal", "luster": "vitreous", "colors": ["pale blue", "blue-green", "greenish-blue"], "common_treatments": ["heat treatment (to remove yellow tones)"], "birthstone_months": [3], "zodiac_signs": ["Scorpio", "Pisces"], "wikidata_qid": "Q102330", "common_simulants": ["blue topaz", "blue zircon", "blue spinel"], "notes": "Iron-colored beryl. Larger clean crystals than emerald are common. 'Santa Maria' and 'Santa Maria Africana' are top color grades.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Topaz", "name_ja": "トパーズ", "mineral_family": "topaz", "chemical_formula": "Al2SiO4(F,OH)2", "mohs_hardness": [8, 8], "refractive_index": [1.610, 1.638], "specific_gravity": [3.49, 3.57], "crystal_system": "orthorhombic", "cleavage": "perfect, basal", "luster": "vitreous", "colors": ["colorless", "blue", "yellow", "pink", "imperial orange-pink", "red"], "common_treatments": ["irradiation + heat (blue topaz)", "coating", "diffusion (mystic topaz)"], "birthstone_months": [11], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q102117", "common_simulants": ["citrine", "smoky quartz", "blue spinel"], "notes": "Most blue topaz on the market is treated colorless topaz (irradiation creates the blue). Imperial topaz (orange-pink to red) is rare and natural. Perfect basal cleavage means careful setting required.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Amethyst", "name_ja": "アメジスト", "mineral_family": "quartz", "chemical_formula": "SiO2 (Fe impurity)", "mohs_hardness": [7, 7], "refractive_index": [1.544, 1.553], "specific_gravity": [2.65, 2.65], "crystal_system": "trigonal", "cleavage": "none", "luster": "vitreous", "colors": ["purple", "violet"], "common_treatments": ["heat treatment (to convert to citrine)", "irradiation"], "birthstone_months": [2], "zodiac_signs": ["Aquarius", "Pisces"], "wikidata_qid": "Q104145", "common_simulants": ["purple glass", "synthetic amethyst", "purple sapphire"], "notes": "Purple variety of quartz. Brazilian and Uruguayan amethyst dominate the market; deep saturated 'Siberian' color is the premium grade. Heat-treating amethyst produces citrine.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Citrine", "name_ja": "シトリン", "mineral_family": "quartz", "chemical_formula": "SiO2 (Fe impurity)", "mohs_hardness": [7, 7], "refractive_index": [1.544, 1.553], "specific_gravity": [2.65, 2.65], "crystal_system": "trigonal", "cleavage": "none", "luster": "vitreous", "colors": ["yellow", "yellow-orange", "brown-orange"], "common_treatments": ["heat treatment (most market citrine is heated amethyst)"], "birthstone_months": [11], "zodiac_signs": ["Gemini", "Aries"], "wikidata_qid": "Q124889", "common_simulants": ["yellow topaz", "yellow sapphire"], "notes": "Yellow variety of quartz. Most commercial citrine is heat-treated amethyst. Natural citrine is paler and slightly smoky. Affordable and durable; common in birthstone jewelry.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Rose Quartz", "name_ja": "ローズクォーツ", "mineral_family": "quartz", "chemical_formula": "SiO2 (Ti/Al impurity)", "mohs_hardness": [7, 7], "refractive_index": [1.544, 1.553], "specific_gravity": [2.65, 2.65], "crystal_system": "trigonal", "cleavage": "none", "luster": "vitreous", "colors": ["pink"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": ["Taurus", "Libra"], "wikidata_qid": "Q244401", "common_simulants": ["pink glass", "pink chalcedony"], "notes": "Massive pink variety of quartz, rarely transparent. Star rose quartz (asterism) caused by rutile inclusions. Mostly cut en cabochon.", "sources": [] }, { "name": "Smoky Quartz", "name_ja": "スモーキークォーツ", "mineral_family": "quartz", "chemical_formula": "SiO2 (radiation-induced)", "mohs_hardness": [7, 7], "refractive_index": [1.544, 1.553], "specific_gravity": [2.65, 2.65], "crystal_system": "trigonal", "cleavage": "none", "luster": "vitreous", "colors": ["brown", "smoky gray", "black (morion)"], "common_treatments": ["irradiation (much market material is artificially irradiated colorless quartz)"], "birthstone_months": [], "zodiac_signs": ["Scorpio"], "wikidata_qid": "Q1057793", "common_simulants": ["smoky topaz (often actually citrine)"], "notes": "Brown variety of quartz, colored by natural or artificial irradiation. 'Cairngorm' is the historical Scottish smoky quartz. Affordable, easily faceted in large sizes.", "sources": [] }, { "name": "Onyx", "name_ja": "オニキス", "mineral_family": "chalcedony", "chemical_formula": "SiO2 (cryptocrystalline)", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.530, 1.539], "specific_gravity": [2.58, 2.64], "crystal_system": "trigonal (cryptocrystalline)", "cleavage": "none", "luster": "vitreous to waxy", "colors": ["black", "black with white bands"], "common_treatments": ["dye (most jet-black onyx is dyed chalcedony)"], "birthstone_months": [], "zodiac_signs": ["Leo"], "wikidata_qid": "Q104752", "common_simulants": ["black glass", "obsidian"], "notes": "Strictly, onyx is banded black-and-white chalcedony. Most market 'onyx' is solid black dyed chalcedony. Used in cameos and intaglios historically.", "sources": [] }, { "name": "Agate", "name_ja": "アゲート", "mineral_family": "chalcedony", "chemical_formula": "SiO2 (cryptocrystalline)", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.530, 1.539], "specific_gravity": [2.58, 2.64], "crystal_system": "trigonal (cryptocrystalline)", "cleavage": "none", "luster": "vitreous to waxy", "colors": ["banded multicolor"], "common_treatments": ["dye", "heat treatment"], "birthstone_months": [], "zodiac_signs": ["Gemini"], "wikidata_qid": "Q190193", "common_simulants": ["dyed chalcedony", "glass"], "notes": "Banded variety of chalcedony. Hundreds of named varieties (moss agate, fire agate, lace agate, etc.). Affordable; common in beads and cabochons.", "sources": [] }, { "name": "Carnelian", "name_ja": "カーネリアン", "mineral_family": "chalcedony", "chemical_formula": "SiO2 (Fe impurity)", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.530, 1.539], "specific_gravity": [2.58, 2.64], "crystal_system": "trigonal (cryptocrystalline)", "cleavage": "none", "luster": "vitreous to waxy", "colors": ["orange", "red-orange", "reddish-brown"], "common_treatments": ["heat treatment (to enhance color)"], "birthstone_months": [], "zodiac_signs": ["Virgo"], "wikidata_qid": "Q1110287", "common_simulants": ["orange glass", "dyed chalcedony"], "notes": "Orange to red variety of chalcedony. Used since antiquity in signet rings and intaglios. The traditional July birthstone in some lapidary traditions.", "sources": [] }, { "name": "Peridot", "name_ja": "ペリドット", "mineral_family": "olivine", "chemical_formula": "(Mg,Fe)2SiO4", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.654, 1.690], "specific_gravity": [3.27, 3.48], "crystal_system": "orthorhombic", "cleavage": "imperfect", "luster": "vitreous, oily", "dispersion": 0.020, "colors": ["yellow-green", "olive-green", "brownish-green"], "common_treatments": ["none typically (untreated)"], "birthstone_months": [8], "zodiac_signs": ["Leo", "Virgo"], "wikidata_qid": "Q188798", "common_simulants": ["green sapphire", "green tourmaline", "chrysoberyl", "green tsavorite"], "notes": "Gem variety of olivine. One of the few gemstones that occurs in only one color (yellowish to olive green). Found in meteorites (pallasites). Egyptian/Pakistani sources historic.", "sources": [] }, { "name": "Tourmaline", "name_ja": "トルマリン", "mineral_family": "tourmaline", "chemical_formula": "(Na,Ca)(Mg,Li,Al,Fe2+)3Al6(BO3)3Si6O18(OH)4", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.624, 1.644], "specific_gravity": [3.00, 3.26], "crystal_system": "trigonal", "cleavage": "indistinct", "luster": "vitreous", "dispersion": 0.017, "colors": ["any color including bicolor and tricolor (watermelon)"], "common_treatments": ["heat treatment", "irradiation"], "birthstone_months": [10], "zodiac_signs": ["Libra", "Leo"], "wikidata_qid": "Q11487", "common_simulants": ["various color-matched stones"], "notes": "Mineral group with widest color range in gemstone family. 'Paraiba' (cuprian) tourmaline (neon blue-green) commands extreme premiums. Rubellite (red), indicolite (blue), and watermelon (pink core with green rim) are notable varieties.", "sources": ["GIA Colored Stone Reports"] }, { "name": "Garnet", "name_ja": "ガーネット", "mineral_family": "garnet", "chemical_formula": "X3Y2(SiO4)3 (X,Y = various)", "mohs_hardness": [6.5, 7.5], "refractive_index": [1.714, 1.890], "specific_gravity": [3.50, 4.30], "crystal_system": "cubic", "cleavage": "none", "luster": "vitreous", "colors": ["red", "orange", "yellow", "green", "purple", "color-change"], "common_treatments": ["none typically (untreated)"], "birthstone_months": [1], "zodiac_signs": ["Capricorn"], "wikidata_qid": "Q102331", "common_simulants": ["ruby", "spinel", "tourmaline"], "notes": "Mineral group with multiple species: pyrope (red), almandine (red), spessartine (orange), grossular incl. tsavorite (green) and hessonite (orange-brown), uvarovite (green), andradite incl. demantoid (green) and melanite (black).", "sources": [] }, { "name": "Tsavorite", "name_ja": "ツァボライト", "mineral_family": "garnet (grossular)", "chemical_formula": "Ca3Al2(SiO4)3 (V, Cr impurities)", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.734, 1.748], "specific_gravity": [3.57, 3.73], "crystal_system": "cubic", "cleavage": "none", "luster": "vitreous", "colors": ["green to vivid green"], "common_treatments": ["none (always untreated)"], "birthstone_months": [1], "zodiac_signs": ["Capricorn"], "wikidata_qid": "Q758005", "common_simulants": ["emerald", "green tourmaline"], "notes": "Vivid green grossular garnet, discovered 1967 in Tanzania. Untreated by definition; harder than emerald and less included. Major source: Tsavo region, Kenya/Tanzania.", "sources": [] }, { "name": "Demantoid", "name_ja": "デマントイドガーネット", "mineral_family": "garnet (andradite)", "chemical_formula": "Ca3Fe2(SiO4)3", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.880, 1.889], "specific_gravity": [3.81, 3.87], "crystal_system": "cubic", "cleavage": "none", "luster": "adamantine", "dispersion": 0.057, "colors": ["green to yellow-green"], "common_treatments": ["none (always untreated)"], "birthstone_months": [1], "zodiac_signs": ["Capricorn"], "wikidata_qid": "Q1183057", "common_simulants": ["peridot", "tsavorite"], "notes": "Andradite garnet variety. Dispersion exceeds diamond — exceptional fire. Russian (Ural Mountains) demantoid with horsetail inclusions of byssolite is the historic premium. Discovered 1853.", "sources": [] }, { "name": "Spinel", "name_ja": "スピネル", "mineral_family": "spinel", "chemical_formula": "MgAl2O4", "mohs_hardness": [7.5, 8.0], "refractive_index": [1.712, 1.762], "specific_gravity": [3.58, 3.61], "crystal_system": "cubic", "cleavage": "imperfect", "luster": "vitreous", "dispersion": 0.020, "colors": ["red", "pink", "blue", "purple", "black", "colorless"], "common_treatments": ["none typically (untreated, exceptional in the trade)"], "birthstone_months": [8], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q190454", "common_simulants": ["ruby", "synthetic spinel"], "notes": "Long mistaken for ruby (the Black Prince's Ruby and Timur Ruby in the British Crown Jewels are both spinels). Untreated by definition. Burmese 'Mahenge' pink spinel commands extreme premiums.", "sources": [] }, { "name": "Tanzanite", "name_ja": "タンザナイト", "mineral_family": "zoisite", "chemical_formula": "Ca2Al3(SiO4)3(OH)", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.691, 1.700], "specific_gravity": [3.10, 3.38], "crystal_system": "orthorhombic", "cleavage": "perfect", "luster": "vitreous", "colors": ["blue", "violet", "blue-violet (trichroic)"], "common_treatments": ["heat treatment (near-universal)"], "birthstone_months": [12], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q424428", "common_simulants": ["sapphire", "iolite", "synthetic forsterite"], "notes": "Blue zoisite from Tanzania, discovered 1967. Mined from a single small area near Mount Kilimanjaro — limited geographic supply. Most market tanzanite is heat-treated to enhance blue. Strong pleochroism (color shift by viewing angle).", "sources": [] }, { "name": "Opal", "name_ja": "オパール", "mineral_family": "opal", "chemical_formula": "SiO2·nH2O", "mohs_hardness": [5.5, 6.5], "refractive_index": [1.450, 1.460], "specific_gravity": [1.98, 2.25], "crystal_system": "amorphous", "cleavage": "none", "luster": "vitreous, waxy", "colors": ["white", "black", "fire orange", "boulder (with matrix)", "crystal", "all colors via play-of-color"], "common_treatments": ["smoke treatment (Andamooka)", "oiling", "polymer impregnation"], "birthstone_months": [10], "zodiac_signs": ["Libra", "Scorpio"], "wikidata_qid": "Q82627", "common_simulants": ["opalescent glass", "synthetic opal (Gilson)"], "notes": "Hydrated silica with characteristic play-of-color (precious opal) from light diffraction off ordered silica spheres. Australian black opal (Lightning Ridge) is the most valuable. Common opal lacks play-of-color. Sensitive to dehydration and impact.", "sources": [] }, { "name": "Pearl", "name_ja": "真珠", "mineral_family": "pearl", "chemical_formula": "CaCO3 (aragonite) + organic conchiolin", "mohs_hardness": [2.5, 4.5], "refractive_index": [1.530, 1.685], "specific_gravity": [2.60, 2.85], "crystal_system": "orthorhombic (aragonite)", "cleavage": "n/a (organic)", "luster": "pearly", "colors": ["white", "cream", "pink", "black", "gold", "blue", "iridescent"], "common_treatments": ["bleaching", "dyeing", "irradiation"], "birthstone_months": [6], "zodiac_signs": ["Cancer"], "wikidata_qid": "Q43100", "common_simulants": ["glass pearls (Majorica)", "shell pearls", "plastic pearls"], "notes": "Organic gem. Akoya (Japanese saltwater, small), South Sea (Australian/Indonesian/Philippine, large, white-gold), Tahitian (French Polynesian, black), and freshwater (China, varied) are the main types. Mostly cultured today; natural pearls are extraordinarily rare and valuable.", "sources": ["CIBJO Pearl Book", "GIA Pearl Reports"] }, { "name": "Lapis Lazuli", "name_ja": "ラピスラズリ", "mineral_family": "lapis lazuli (rock)", "chemical_formula": "lazurite + calcite + pyrite", "mohs_hardness": [5.0, 6.0], "refractive_index": [1.500, 1.500], "specific_gravity": [2.50, 3.00], "crystal_system": "cubic (lazurite)", "cleavage": "n/a (rock)", "luster": "vitreous to greasy", "colors": ["deep blue with golden pyrite specks"], "common_treatments": ["wax/oil impregnation", "dye (poor-quality material)"], "birthstone_months": [12], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q150586", "common_simulants": ["dyed howlite", "sodalite", "glass"], "notes": "Rock (not a single mineral). Historic source: Sar-e-Sang mines, Badakhshan, Afghanistan (mined for 6,000+ years). Used for ultramarine pigment in Renaissance painting.", "sources": [] }, { "name": "Turquoise", "name_ja": "ターコイズ", "mineral_family": "turquoise", "chemical_formula": "CuAl6(PO4)4(OH)8·4H2O", "mohs_hardness": [5.0, 6.0], "refractive_index": [1.610, 1.650], "specific_gravity": [2.60, 2.91], "crystal_system": "triclinic", "cleavage": "good", "luster": "waxy", "colors": ["sky blue", "blue-green", "green"], "common_treatments": ["stabilization (polymer impregnation, near-universal)", "wax", "dye", "reconstitution"], "birthstone_months": [12], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q188043", "common_simulants": ["dyed howlite", "magnesite (dyed)", "imitation turquoise", "chrysocolla"], "notes": "Hydrous copper-aluminum phosphate. Naturally porous; almost universally stabilized for jewelry use. Persian (Iranian) and Sleeping Beauty (Arizona, mine closed) are premium sources. Sacred in Indigenous Southwestern US and Tibetan traditions.", "sources": [] }, { "name": "Moonstone", "name_ja": "ムーンストーン", "mineral_family": "feldspar (orthoclase + albite)", "chemical_formula": "K(AlSi3O8) + Na(AlSi3O8)", "mohs_hardness": [6.0, 6.5], "refractive_index": [1.518, 1.526], "specific_gravity": [2.56, 2.62], "crystal_system": "monoclinic", "cleavage": "perfect", "luster": "vitreous, pearly on cleavage", "colors": ["white", "blue", "rainbow", "peach", "gray"], "common_treatments": ["none typically"], "birthstone_months": [6], "zodiac_signs": ["Cancer", "Libra"], "wikidata_qid": "Q1058334", "common_simulants": ["chalcedony", "milky quartz", "opal"], "notes": "Feldspar with characteristic adularescence (billowy blue-white sheen from layered orthoclase/albite). Sri Lankan blue moonstone is the premium. Rainbow moonstone is actually labradorite from India.", "sources": [] }, { "name": "Labradorite", "name_ja": "ラブラドライト", "mineral_family": "feldspar (plagioclase)", "chemical_formula": "(Ca,Na)(Al,Si)4O8", "mohs_hardness": [6.0, 6.5], "refractive_index": [1.559, 1.573], "specific_gravity": [2.68, 2.72], "crystal_system": "triclinic", "cleavage": "perfect", "luster": "vitreous, pearly", "colors": ["dark gray base with flash blue, gold, green, orange (labradorescence)"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": ["Leo"], "wikidata_qid": "Q47104", "common_simulants": ["spectrolite (gem variety of same)", "andesine (treated)"], "notes": "Plagioclase feldspar with iridescent 'labradorescence' (light interference from lamellar structure). Finnish 'spectrolite' is a particularly vivid variety. Discovered Labrador, Canada, 1770.", "sources": [] }, { "name": "Iolite", "name_ja": "アイオライト", "mineral_family": "cordierite", "chemical_formula": "(Mg,Fe)2Al4Si5O18", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.522, 1.578], "specific_gravity": [2.58, 2.66], "crystal_system": "orthorhombic", "cleavage": "indistinct", "luster": "vitreous", "colors": ["blue-violet", "with strong trichroism"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q420017", "common_simulants": ["tanzanite", "blue sapphire"], "notes": "Gem cordierite. Strong trichroism — looks blue, light blue, and yellow from three angles. Called the 'Viking compass stone' for purported use as a polarizing filter in cloudy navigation.", "sources": [] }, { "name": "Zircon", "name_ja": "ジルコン", "mineral_family": "zircon", "chemical_formula": "ZrSiO4", "mohs_hardness": [6.0, 7.5], "refractive_index": [1.810, 2.024], "specific_gravity": [3.93, 4.73], "crystal_system": "tetragonal", "cleavage": "imperfect", "luster": "vitreous to adamantine", "dispersion": 0.039, "colors": ["colorless", "blue", "yellow", "brown", "red"], "common_treatments": ["heat treatment (most blue zircon)"], "birthstone_months": [12], "zodiac_signs": ["Sagittarius"], "wikidata_qid": "Q21070", "common_simulants": ["diamond (colorless zircon historically)", "cubic zirconia (CZ — different material)"], "notes": "Natural zircon — NOT to be confused with synthetic cubic zirconia (CZ), which is a completely different material. Zircon has high dispersion and was used as a diamond simulant historically. Cambodian blue zircon is the premium.", "sources": [] }, { "name": "Chrysoberyl", "name_ja": "クリソベリル", "mineral_family": "chrysoberyl", "chemical_formula": "BeAl2O4", "mohs_hardness": [8.5, 8.5], "refractive_index": [1.741, 1.760], "specific_gravity": [3.71, 3.75], "crystal_system": "orthorhombic", "cleavage": "imperfect", "luster": "vitreous", "colors": ["yellow-green", "yellow", "brown"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q420876", "common_simulants": ["peridot", "yellow sapphire"], "notes": "Beryllium aluminum oxide. Two famous varieties: alexandrite (color-change red/green) and cat's-eye chrysoberyl (chatoyancy). Hardness 8.5 makes it one of the most durable colored gems.", "sources": [] }, { "name": "Alexandrite", "name_ja": "アレキサンドライト", "mineral_family": "chrysoberyl", "chemical_formula": "BeAl2O4 (Cr impurity)", "mohs_hardness": [8.5, 8.5], "refractive_index": [1.741, 1.760], "specific_gravity": [3.71, 3.75], "crystal_system": "orthorhombic", "cleavage": "imperfect", "luster": "vitreous", "colors": ["green in daylight, red in incandescent light (color change)"], "common_treatments": ["none typically"], "birthstone_months": [6], "zodiac_signs": ["Gemini"], "wikidata_qid": "Q258266", "common_simulants": ["synthetic color-change corundum", "synthetic alexandrite"], "notes": "Color-change variety of chrysoberyl. Discovered Russia 1834. Strongest color change in nature ('emerald by day, ruby by night'). Russian Ural alexandrite with strong change commands extreme premiums.", "sources": [] }, { "name": "Morganite", "name_ja": "モルガナイト", "mineral_family": "beryl", "chemical_formula": "Be3Al2(SiO3)6 (Mn impurity)", "mohs_hardness": [7.5, 8.0], "refractive_index": [1.580, 1.598], "specific_gravity": [2.71, 2.90], "crystal_system": "hexagonal", "cleavage": "imperfect", "luster": "vitreous", "colors": ["pink", "peach", "salmon"], "common_treatments": ["heat treatment (to remove yellow tones)", "irradiation"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q259375", "common_simulants": ["pink sapphire", "kunzite"], "notes": "Pink beryl, named for J.P. Morgan. Major source: Brazil and Madagascar. Increasingly popular in bridal jewelry as a sapphire alternative.", "sources": [] }, { "name": "Heliodor", "name_ja": "ヘリオドール", "mineral_family": "beryl", "chemical_formula": "Be3Al2(SiO3)6 (Fe impurity)", "mohs_hardness": [7.5, 8.0], "refractive_index": [1.570, 1.585], "specific_gravity": [2.69, 2.78], "crystal_system": "hexagonal", "cleavage": "imperfect", "luster": "vitreous", "colors": ["yellow", "golden yellow", "greenish yellow"], "common_treatments": ["irradiation"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q11422088", "common_simulants": ["citrine", "yellow sapphire"], "notes": "Yellow to golden beryl. Often grouped with 'golden beryl' as the same material. Strong, clear, affordable yellow gem.", "sources": [] }, { "name": "Kunzite", "name_ja": "クンツァイト", "mineral_family": "spodumene", "chemical_formula": "LiAl(SiO3)2 (Mn impurity)", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.660, 1.676], "specific_gravity": [3.15, 3.21], "crystal_system": "monoclinic", "cleavage": "perfect", "luster": "vitreous", "colors": ["pink", "violet-pink"], "common_treatments": ["irradiation (to enhance color)"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q1085037", "common_simulants": ["morganite", "pink sapphire"], "notes": "Pink variety of spodumene. Named for George Kunz (Tiffany's gemologist). Strong pleochroism. Color may fade in prolonged sunlight ('evening stone'). Two perfect cleavages — challenging to cut.", "sources": [] }, { "name": "Hiddenite", "name_ja": "ヒデナイト", "mineral_family": "spodumene", "chemical_formula": "LiAl(SiO3)2 (Cr impurity)", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.660, 1.676], "specific_gravity": [3.15, 3.21], "crystal_system": "monoclinic", "cleavage": "perfect", "luster": "vitreous", "colors": ["green", "yellow-green"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q1601822", "common_simulants": ["emerald", "tsavorite"], "notes": "Green chromium-bearing variety of spodumene. Discovered Hiddenite, North Carolina, USA. Rare; small in clean sizes.", "sources": [] }, { "name": "Apatite", "name_ja": "アパタイト", "mineral_family": "apatite", "chemical_formula": "Ca5(PO4)3(F,Cl,OH)", "mohs_hardness": [5, 5], "refractive_index": [1.634, 1.638], "specific_gravity": [3.16, 3.22], "crystal_system": "hexagonal", "cleavage": "imperfect", "luster": "vitreous", "colors": ["blue", "green", "yellow", "purple", "pink"], "common_treatments": ["heat treatment"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q132851", "common_simulants": ["paraiba tourmaline", "blue zircon"], "notes": "Mohs 5 is too soft for everyday rings but acceptable for pendants and earrings. Neon blue Madagascar apatite resembles Paraiba tourmaline at a fraction of the price.", "sources": [] }, { "name": "Diopside", "name_ja": "ダイオプサイド", "mineral_family": "pyroxene", "chemical_formula": "CaMgSi2O6", "mohs_hardness": [5.5, 6.5], "refractive_index": [1.668, 1.700], "specific_gravity": [3.20, 3.40], "crystal_system": "monoclinic", "cleavage": "good", "luster": "vitreous", "colors": ["green (chrome diopside)", "black star", "blue"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q409008", "common_simulants": ["emerald", "tsavorite", "peridot"], "notes": "Chrome diopside (Russian, Siberian) is a vivid green, affordable emerald alternative. Black star diopside shows four-rayed asterism.", "sources": [] }, { "name": "Sphene", "name_ja": "スフェーン", "mineral_family": "titanite", "chemical_formula": "CaTiSiO5", "mohs_hardness": [5.0, 5.5], "refractive_index": [1.880, 2.110], "specific_gravity": [3.50, 3.60], "crystal_system": "monoclinic", "cleavage": "imperfect", "luster": "adamantine to resinous", "dispersion": 0.051, "colors": ["yellow", "green", "brown", "orange"], "common_treatments": ["heat treatment"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q409064", "common_simulants": ["demantoid", "peridot"], "notes": "Also called titanite. Dispersion higher than diamond — exceptional fire. Soft (Mohs 5) so prone to scratching; best in protected settings.", "sources": [] }, { "name": "Andalusite", "name_ja": "アンダルサイト", "mineral_family": "andalusite", "chemical_formula": "Al2SiO5", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.633, 1.644], "specific_gravity": [3.13, 3.20], "crystal_system": "orthorhombic", "cleavage": "good", "luster": "vitreous", "colors": ["yellow-brown to green with strong pleochroism (yellow + reddish-brown + green)"], "common_treatments": ["none typically"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q132568", "common_simulants": ["alexandrite (color-change)"], "notes": "Strong trichroism shows multiple colors simultaneously from one viewing angle. Different optical phenomenon from alexandrite. Brazilian and Spanish (Andalusia, namesake) sources.", "sources": [] }, { "name": "Spessartine", "name_ja": "スペサルティンガーネット", "mineral_family": "garnet", "chemical_formula": "Mn3Al2(SiO4)3", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.780, 1.810], "specific_gravity": [4.12, 4.20], "crystal_system": "cubic", "cleavage": "none", "luster": "vitreous", "colors": ["orange", "yellow-orange", "red-orange"], "common_treatments": ["none typically"], "birthstone_months": [1], "zodiac_signs": ["Capricorn"], "wikidata_qid": "Q414218", "common_simulants": ["hessonite", "orange sapphire"], "notes": "Manganese garnet. 'Mandarin garnet' (vivid orange from Namibia) is the premium. Discovered Spessart district, Germany.", "sources": [] }, { "name": "Hessonite", "name_ja": "ヘソナイト", "mineral_family": "garnet (grossular)", "chemical_formula": "Ca3Al2(SiO4)3 (Fe, Mn impurities)", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.738, 1.745], "specific_gravity": [3.57, 3.73], "crystal_system": "cubic", "cleavage": "none", "luster": "vitreous", "colors": ["orange-brown", "honey", "cinnamon"], "common_treatments": ["none typically"], "birthstone_months": [1], "zodiac_signs": ["Capricorn"], "wikidata_qid": "Q1147495", "common_simulants": ["citrine", "topaz"], "notes": "'Cinnamon stone' grossular garnet. Characteristic 'treacle' (heat-shimmer) inclusions. Affordable and durable.", "sources": [] }, { "name": "Rhodolite", "name_ja": "ロードライトガーネット", "mineral_family": "garnet (pyrope-almandine)", "chemical_formula": "(Mg,Fe)3Al2(SiO4)3", "mohs_hardness": [7.0, 7.5], "refractive_index": [1.745, 1.760], "specific_gravity": [3.74, 3.94], "crystal_system": "cubic", "cleavage": "none", "luster": "vitreous", "colors": ["raspberry red", "purplish-red", "rose-red"], "common_treatments": ["none typically"], "birthstone_months": [1], "zodiac_signs": ["Capricorn"], "wikidata_qid": "Q2226218", "common_simulants": ["ruby", "spinel"], "notes": "Pyrope-almandine garnet blend with distinctive raspberry-pink to purple-red. Tanzanian and Mozambican sources are notable. Brighter and clearer than typical almandine.", "sources": [] }, { "name": "Jade (Jadeite)", "name_ja": "ジェダイト (硬玉)", "mineral_family": "pyroxene (jadeite)", "chemical_formula": "NaAlSi2O6", "mohs_hardness": [6.5, 7.0], "refractive_index": [1.652, 1.688], "specific_gravity": [3.30, 3.38], "crystal_system": "monoclinic", "cleavage": "good (interlocked, tough)", "luster": "vitreous to greasy", "colors": ["green (incl. imperial)", "lavender", "white", "yellow", "black"], "common_treatments": ["impregnation (Type B, C, B+C)", "dye"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q186618", "common_simulants": ["nephrite jade", "serpentine", "dyed quartz"], "notes": "True jade alongside nephrite. Imperial green (translucent vivid green) Burmese jadeite is the premium gem. Sold by GIA grading: Type A (untreated), B (impregnated), C (dyed), B+C.", "sources": ["GIA Jade Type System"] }, { "name": "Jade (Nephrite)", "name_ja": "ネフライト (軟玉)", "mineral_family": "amphibole", "chemical_formula": "Ca2(Mg,Fe)5Si8O22(OH)2", "mohs_hardness": [6.0, 6.5], "refractive_index": [1.600, 1.640], "specific_gravity": [2.90, 3.03], "crystal_system": "monoclinic", "cleavage": "interlocked fibrous (extreme toughness)", "luster": "vitreous to greasy", "colors": ["dark green", "spinach green", "white (mutton-fat)", "black"], "common_treatments": ["wax"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q186618", "common_simulants": ["serpentine", "jadeite"], "notes": "Other true jade. Historic Chinese jade is mostly nephrite. Exceptional toughness (highest of any gemstone) — used for tool blades in antiquity. White 'mutton-fat' nephrite is the premium Chinese variety.", "sources": [] }, { "name": "Coral", "name_ja": "サンゴ", "mineral_family": "coral", "chemical_formula": "CaCO3 (calcite) + organic", "mohs_hardness": [3, 4], "refractive_index": [1.486, 1.658], "specific_gravity": [2.60, 2.70], "crystal_system": "n/a (organic)", "cleavage": "n/a", "luster": "dull to vitreous", "colors": ["red", "pink (angelskin)", "white", "black"], "common_treatments": ["dye", "wax"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q11427", "common_simulants": ["dyed bone", "plastic"], "notes": "Organic gem from marine coral polyps. Mediterranean and Japanese Akamomo (red) and Sardegna are historic sources. CITES-regulated due to endangered species. Soft (Mohs 3-4) — requires gentle handling.", "sources": ["CITES Appendix II/III"] }, { "name": "Amber", "name_ja": "琥珀", "mineral_family": "amber (organic)", "chemical_formula": "C10H16O (fossil resin)", "mohs_hardness": [2.0, 2.5], "refractive_index": [1.539, 1.545], "specific_gravity": [1.05, 1.10], "crystal_system": "amorphous", "cleavage": "none", "luster": "resinous", "colors": ["honey yellow", "orange", "red", "green", "blue (rare)"], "common_treatments": ["heat treatment", "pressing (reconstituted amber)"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q25381", "common_simulants": ["copal (younger resin)", "plastic", "glass"], "notes": "Fossilized tree resin, often containing insect/plant inclusions. Baltic amber (40-50 million years old) and Dominican amber (clear blue variety) are notable. Floats in saltwater — a useful test. Very soft.", "sources": [] }, { "name": "Lab-grown diamond", "name_ja": "ラボグロウンダイヤモンド", "mineral_family": "diamond", "chemical_formula": "C", "mohs_hardness": [10, 10], "refractive_index": [2.417, 2.419], "specific_gravity": [3.50, 3.53], "crystal_system": "cubic", "cleavage": "perfect, octahedral", "luster": "adamantine", "dispersion": 0.044, "colors": ["colorless", "yellow", "pink", "blue"], "common_treatments": ["HPHT post-treatment", "irradiation"], "birthstone_months": [4], "zodiac_signs": ["Aries", "Taurus"], "wikidata_qid": "Q1141158", "common_simulants": ["moissanite", "cubic zirconia"], "notes": "Synthetic diamond grown by HPHT (high-pressure high-temperature) or CVD (chemical vapor deposition). Physically and chemically identical to natural diamond. Distinguishable only by spectroscopic testing (presence of CVD growth striae, HPHT cuboctahedral growth pattern). Per FTC, must be disclosed as 'lab-grown', 'synthetic', or 'man-made'.", "sources": ["FTC Jewelry Guide 16 CFR Part 23.20"] }, { "name": "Moissanite", "name_ja": "モアサナイト", "mineral_family": "moissanite (silicon carbide)", "chemical_formula": "SiC", "mohs_hardness": [9.25, 9.25], "refractive_index": [2.648, 2.691], "specific_gravity": [3.21, 3.22], "crystal_system": "hexagonal", "cleavage": "n/a (no significant cleavage)", "luster": "adamantine", "dispersion": 0.104, "colors": ["colorless", "yellow", "green"], "common_treatments": ["none (synthetic by definition in jewelry trade)"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q422211", "common_simulants": ["diamond"], "notes": "Silicon carbide (SiC). Naturally extremely rare (originally found in meteorites); all jewelry moissanite is synthetic. Higher dispersion than diamond → more rainbow flash. Distinguishable from diamond by doubling visible through facet (birefringent), and by moissanite-specific testers.", "sources": [] }, { "name": "Cubic Zirconia", "name_ja": "キュービックジルコニア", "mineral_family": "synthetic", "chemical_formula": "ZrO2 (stabilized)", "mohs_hardness": [8.0, 8.5], "refractive_index": [2.150, 2.180], "specific_gravity": [5.65, 5.95], "crystal_system": "cubic", "cleavage": "none", "luster": "adamantine", "dispersion": 0.060, "colors": ["any (typically colorless)"], "common_treatments": ["color doping (yttrium, cerium, copper for color)"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q422211", "common_simulants": ["diamond"], "notes": "Synthetic. Not the same as zircon (a natural mineral). Inexpensive diamond simulant. Distinguishable from diamond by density (much heavier), thermal conductivity, and lower hardness (scratches over time).", "sources": [] }, { "name": "Synthetic Sapphire", "name_ja": "合成サファイア", "mineral_family": "corundum (synthetic)", "chemical_formula": "Al2O3", "mohs_hardness": [9, 9], "refractive_index": [1.762, 1.770], "specific_gravity": [3.97, 4.05], "crystal_system": "trigonal", "cleavage": "none", "luster": "vitreous", "colors": ["any"], "common_treatments": ["lattice diffusion"], "birthstone_months": [], "zodiac_signs": [], "wikidata_qid": "Q4118", "common_simulants": [], "notes": "Synthetic corundum produced by flame fusion (Verneuil), flux growth, or hydrothermal. Physically identical to natural sapphire. Must be disclosed as 'synthetic' or 'lab-created' per FTC.", "sources": ["FTC Jewelry Guide 16 CFR Part 23.20"] } ]