Goals

Amazonite is the green to blue-green variety of potassium feldspar, usually microcline (the name is sometimes also applied to green orthoclase), with the formula KAlSi₃O₈. Its color is usually attributed to small amounts of lead. It is also called Amazon stone (amazonstone).

Aqua Aura is a trade name for treated natural quartz: colorless rock crystal coated with an extremely thin film of gold, which gives it a light blue to greenish-blue color and a strong iridescent sheen. The quartz itself is natural, but the color is artificial and lies only on the surface; it is not a natural blue stone and not aquamarine.

Azurmalachite is a natural rock made of two intergrown copper carbonate minerals: blue azurite, Cu3(CO3)2(OH)2, and green malachite, Cu2(CO3)(OH)2. Its name combines the names of the two minerals, and it is also called azurite-malachite or "bluebird". It shows bands, concentric patterns and mottling in blue and green, and is soft (Mohs 3.5 to 4).

"Black jade" is a trade term for black or nearly black natural jade, not a single mineral. Gemologists note that it can cover different pyroxene jades: black jadeite, which is mostly jadeite colored by tiny dark inclusions such as carbon, and "inky black" omphacite jade, which looks black in reflected light but green in transmitted light. Nephrite, the other jade, also occurs in black. Because the name is potentially confusing, the actual material of a black jade piece can only be confirmed by testing.

Black matrix opal is a trade name for precious opal finely distributed through a host rock (matrix) with a dark background. The best-documented material is Andamooka matrix opal from South Australia: a cream to grayish white porous rock with specks of precious opal that is usually blackened by sugar-acid carbon treatment. Such stones are therefore commonly a treated natural material, not natural black opal; naturally dark matrix opal in black volcanic rock is also reported from Honduras and Nicaragua.

Black spinel is opaque black spinel, a natural mineral: magnesium aluminium oxide (MgAl₂O₄) with a high iron content that makes it look black. Iron-rich dark spinel has traditionally been called ceylonite or pleonaste. Black spinel from Bo Phloi, Thailand, contains about 20.7 wt% FeO and shows its true greyish-brown colour only in slices much thinner than 0.1 mm.

Black tiger's eye is a trade name for tiger's eye, a chatoyant variety of quartz containing altered crocidolite (amphibole) fibres, with a black body colour; in the trade it is usually a treated natural material coloured by dye. The gemmologist R. Webster described black tiger's eye cabochons as obviously stained, and the Japanese retailer Pascle states that almost all of its black tiger's eye is artificially dyed, adding that rare natural material is reported but hard to tell apart.

Blue aventurine is a blue colour variety of aventurine, a natural quartzite or quartz rock whose platy inclusions can make it glitter (aventurescence); included dumortierite, a blue borosilicate mineral, produces the blue colour. Much blue material in the bead trade shows little sparkle: the Japanese retailer Pascle says its blue aventurine is for that reason also called blue quartzite. It overlaps with dumortierite quartz, and blue quartz-based beads may also be dyed.

Blue calcite is a descriptive name for natural calcite (calcium carbonate, CaCO₃) with a blue colour; it is a colour variety, not a separate mineral species, and natural blue calcite is described as relatively rare. Its colour cause differs between deposits and remains debated: studies have linked it to defects from natural radiation, to transition metals such as iron, chromium, nickel and copper (Central Anatolia, Turkey), to copper in cave deposits and to trace elements in calcite from Madagascar.

Blue fluorite is the blue color variety of fluorite, the natural calcium fluoride mineral CaF₂. Blue crystals are less common than purple, green or yellow ones. Studies link the blue color mainly to yttrium-associated color centers (an yttrium ion paired with an anion vacancy holding electrons); Geology.com notes that trace yttrium substituting for calcium can cause it.

Blue goldstone is a man-made glass, not a natural stone or mineral. It is the dark blue colour of goldstone (aventurine glass): the glass is coloured blue by cobalt, and tiny flat metallic crystals inside it give a starry, silvery sparkle. Despite the name it contains no gold, and it is not natural blue aventurine quartz or lapis lazuli, which it can resemble.

Blue tourmaline is a natural mineral: the blue color range of tourmaline, a group of closely related borosilicate mineral species. GIA uses the trade name indicolite for dark violetish blue, blue or greenish blue tourmaline, and Mindat describes indicolite as a blue gem variety of tourmaline, usually but not always elbaite or fluor-elbaite. Vivid blue tourmaline colored by copper is sold separately as Paraíba tourmaline.

Bronzite is a natural mineral: an iron-bearing variety of enstatite, a magnesium-rich orthopyroxene, named for the bronze-like, submetallic luster of its cleavage surfaces. Bronzite is not a separate species; since the 1988 pyroxene nomenclature it is classed as enstatite. Polished material is greenish brown to brown with a bronze sheen.

Carnelian (also spelled cornelian) is a translucent orange, reddish or brownish-red variety of chalcedony, the microcrystalline form of quartz (SiO₂). Its color comes from iron oxide impurities. The closely related, darker and browner sard is not sharply separated from carnelian.

Chrome diopside is the chromium-bearing, intensely green variety of the natural mineral diopside (CaMgSi2O6, a pyroxene). Chromium, typically about 0.5% and up to about 2% as Cr2O3, gives it a saturated green similar to emerald. Gem material comes mainly from Yakutia (Sakha Republic) in eastern Siberia, Russia, and is usually cut in small sizes because larger stones look very dark.

Chrysoprase is a natural, translucent, yellowish-green to green variety of chalcedony (microcrystalline quartz, SiO₂) colored by tiny inclusions of nickel compounds. Its name comes from the Greek for "golden leek" (also rendered "golden apple"). Australia is the leading producer today. It is distinct from dyed green chalcedony and from so-called "lemon chrysoprase", which is a magnesite rock.

In this sense, rainbow quartz is a trade name for treated natural quartz: colorless quartz coated in a vacuum with an extremely thin metallic film that gives its surface a rainbow-colored iridescence. The quartz is natural, but the colors are artificial and lie only on the surface. The same name is also used for naturally iridescent quartz (iris quartz), which is a different material.

Crackle quartz is treated natural quartz, not a separate mineral: the quartz is heated and then plunged into water, and the thermal shock fills it with a network of fine internal fractures ("quench crackling"). The fractures can show iridescent colors and also let dye enter, so crackled quartz is often dyed, sometimes to imitate more valuable gems.

Dalmatian stone, widely sold as "Dalmatian jasper", is a natural igneous rock, not a jasper. A 2017 Gems & Gemology study identified it as a peralkaline rock (microgranite, aplite or rhyolite) made mostly of feldspar (mesoperthite) and quartz, whose black spots are the alkali amphibole arfvedsonite. The authors recommend the name "dalmatian stone" because the material does not meet the gemological definition of jasper.

Dumortierite is a natural aluminium borosilicate mineral that usually occurs as massive, fibrous or granular material in blue, violet-blue, pink or reddish brown. Massive blue and violet dumortierite is cut into cabochons and beads, while transparent faceted stones are very rare. It is a distinct mineral and should not be confused with dumortierite quartz, quartz rock coloured by dumortierite.

A dzi (Tibetan gzi; Chinese tianzhu, "heavenly bead") is a bead of natural agate or chalcedony whose black-and-white pattern, typically eyes and stripes, was made by people by staining and etching the stone. Ancient dzi have been excavated from tombs about 2,000 years old in Tibet and Xinjiang. Most dzi on today's market are modern beads made in the same style, and imitations of glass, plastic, resin or metal also exist.

Fluorite, also called fluorspar, is the calcium fluoride mineral CaF₂, a halide. It occurs in a very wide range of colors, including purple, green, blue, yellow, pink and colorless, and crystals are often color zoned. It defines hardness 4 on the Mohs scale.

Garnet is not a single mineral but a group of closely related silicate minerals that share the same crystal structure and differ in chemical composition. Five species are commercially important as gems: pyrope, almandine, spessartine, grossular and andradite; a sixth, uvarovite, usually forms crystals too small to cut. Many garnets are chemical mixtures of two or more species. Garnets occur in almost every color, and red garnet is one of the most common and widespread gems.

Gibeon is a specific iron meteorite from Namibia, named after Gibeon, the area at the centre of its large strewn field. The Meteoritical Bulletin classifies it as an iron of chemical group IVA; it is a fine octahedrite whose etched surface shows a fine Widmanstätten pattern. Beads and jewellery cut from it are natural meteorite metal, but they are commonly plated (for example with rhodium) to slow rusting.

Goldstone is a man-made glass, not a natural stone or mineral. Its glitter comes from tiny flat crystals of metallic copper that grow inside the glass during slow cooling under oxygen-poor conditions. It is also called aventurine glass; it should not be confused with natural aventurine quartz or sunstone, which it is often used to imitate.

Green fluorite is the green color variety of fluorite, the natural calcium fluoride mineral CaF₂. Green is one of fluorite's most typical colors, ranging from pale to deep and bluish green. Pure fluorite is colorless; studies attribute green to color centers linked to trace samarium (Sm²⁺) and to yttrium–cerium-associated centers. Fluorite has been offered as emerald, but it is a much softer, different mineral.

Green garnet is a color-based trade name for natural garnet, not a single mineral species. GIA names tsavorite and demantoid as green garnets: tsavorite is a green, chromium- and vanadium-bearing variety of grossular, and demantoid is the green to yellowish green variety of andradite. Other green grossulars, such as light "mint" garnet from Merelani, Tanzania, are also sold, while green uvarovite usually forms crystals too small to cut. A stone or bead sold as green garnet may therefore be any of these unless tested.

Green tiger's eye is a treated natural material: tiger's eye, a chatoyant variety of quartz containing altered crocidolite (amphibole) fibres, that has been dyed green. Tiger's eye does not naturally occur in this vivid green; gemmological references list dyeing (sometimes after bleaching) as a treatment of tiger's eye, and the Japanese retailer Pascle states that its green tiger's eye is artificially dyed.

Green tourmaline is a natural mineral: the green color range of tourmaline, a group of closely related borosilicate mineral species. Its trade name verdelite is described by Mindat as a green variety of tourmaline, most commonly elbaite or fluor-elbaite, with various other species possible. IGS reserves verdelite for green stones not colored by chromium or vanadium; intense green stones colored by those elements are sold as chrome tourmaline.

Hypersthene is an old name for a natural magnesium–iron orthopyroxene midway between enstatite and ferrosilite. The International Mineralogical Association discarded the name in 1988, so it is no longer a mineral species; Mindat notes that most material called hypersthene is iron-bearing (ferroan) enstatite. The name survives in the gem and bead trade for dark stones with a metallic-looking sheen (schiller).

Imperial topaz is a variety and marketing name for fine natural topaz in warm colors, but it has no single official definition. GIA describes it as medium reddish orange to orange-red, and many dealers require a reddish pleochroic color; Mindat notes the name has expanded over time from pink Russian topaz to orange Ouro Preto topaz and to pinks, reds and peach tones. In Japan, the laboratory association AGL allows "Imperial topaz" as an alias for OH-type topaz.

Iris quartz is natural quartz that shows rainbow-colored iridescence inside or on the crystal without any coating. In gemology the name usually refers to quartz whose colors come from thin films of air in internal cracks; it is also used for crystals from India whose iridescence comes from a finely etched surface structure. It is different from metal-coated "rainbow quartz", and similar iridescent cracks can also be produced artificially by quench crackling.

Itoigawa jade is natural jadeite jade (jadeitite, a rock made mostly of the mineral jadeite) from Itoigawa City, Niigata Prefecture, Japan's largest jade source. It formed about 520 million years ago and is described locally as the world's oldest jade. In 2016 the Japanese Association of Mineralogical Sciences chose jade (jadeite and jadeitite) as Japan's national stone; Itoigawa is the locality where gem-quality material is abundant.

Jadeite is a natural rock made of tiny interlocking crystals of the pyroxene mineral jadeite (NaAlSi₂O₆), and it is one of the two classic materials called jade. The other, nephrite, is a different material made of amphibole minerals; the two look alike, which is why both were long sold as "jade", but the French mineralogist Alexis Damour separated them in 1863. In Chinese, 翡翠 (fei cui) is a traditional term for jadeite jade, though in parts of Asia it is also applied to kosmochlor and omphacite. Jadeite is generally the rarer and more valuable of the two.

Kamuikotan stone (Kamuikotan-seki) is a natural metamorphic rock, not a single mineral: a hard, compact, dark blue-green to black rock collected as river boulders in the Kamuikotan gorge of the Ishikari River in Asahikawa, Hokkaido. Japanese reference works describe it as an alkali-amphibole-bearing mafic to siliceous metamorphic rock, and it is one of Hokkaido's best-known viewing stones (suiseki) and garden stones.

Kyanite is an aluminum silicate mineral (Al₂SiO₅) that forms during the regional metamorphism of clay-rich sediments. It shares its chemistry with andalusite and sillimanite (polymorphs). It is most often blue and grows as elongated blades whose hardness varies with direction. Synonyms include cyanite and disthene (also spelled distene). It is a raw material for refractory porcelain, and clear, deep blue material is cut as a gemstone.

Lapis lazuli is a blue rock containing several minerals.

Larvikite is a natural igneous rock, not a single mineral: a coarse-grained monzonite (augite syenite to monzonite) from the area around Larvik in south-eastern Norway. It consists mostly of ternary feldspar crystals whose fine internal lamellae produce a blue to silvery sheen (schiller) on polished surfaces. It is Norway's national rock and one of the world's best-known ornamental building stones.

Lepidolite is a natural lithium-rich mica, usually pink, red or purple. It is not a single IMA mineral species: Mindat describes it as a field name for the Li-rich micas in or near the polylithionite–trilithionite series (also fluorluanshiweiite and luanshiweiite). Its color comes mainly from manganese, not lithium, and gem material is often lepidolite impregnated with quartz.

Orange calcite is a descriptive name for natural calcite (calcium carbonate, CaCO₃) of orange to orangy-yellow colour; it is a colour variety, not a separate mineral species. Gem laboratories have documented orangy-yellow calcite from Pakistan and Mexico and yellowish-orange calcite from the Czech Republic. The sources consulted do not establish a cause for the orange colour, and the Japanese retailer Pascle notes that the boundary with yellow calcite is not defined, so names vary between sellers.

Orange garnet is a color-based trade name for natural garnet, not a single mineral species. GIA identifies spessartine (also called spessartite), a manganese aluminum garnet, as an orange garnet, and its purest, vivid orange form is sold as mandarin garnet; hessonite, the orange to brownish variety of grossular garnet, is also orange. Many garnets are mixtures of species, so a stone or bead sold as orange garnet may be either unless tested.

Petrified wood is a plant fossil, not wood and not a single mineral species: it is ancient wood whose pores were filled and whose tissue was partly or wholly replaced by silica, so that it is now made mostly of quartz while keeping the shape and often the cell structure of the tree. Paleontologists describe the processes as permineralization and replacement; silicification (by silica) is the most common type in fossil wood.

Picture jasper is a natural rock material: jasper, an opaque, dense microcrystalline quartz, whose patterns resemble pictures of natural scenery. It is also called scenic jasper. It is typically light tan with dark brown lines that, when cut in certain directions, look like landscapes such as rolling hills or shorelines.

Pietersite is a natural brecciated rock (a gem material, not a single mineral species) made of fine-grained quartz or chalcedony with embedded fibres of crocidolite, an amphibole, in various stages of alteration to iron oxides. The fibres give it a chaotic, multi-directional chatoyancy in blue-gray, golden yellow, brown and red. It is often described as a brecciated tiger's eye or hawk's eye; mineral databases classify it as a variety of chalcedony. It is also called Tempest stone.

Pink tiger's eye is natural tiger's eye, a chatoyant variety of quartz, that has been dyed pink; it is a treated natural material, not a naturally pink variety. Gemological references describe natural tiger's eye in golden to brown tones and in blue (hawk's eye), and Gemdat and IGS state that it can be dyed to any colour. The Japanese retailer Pascle also states that its pink tiger's eye is artificially dyed.

Poppy jasper is a natural rock material: a trade name for orbicular jasper, an opaque microcrystalline quartz, containing scattered, relatively bright red, orange or yellow orbicules (roughly spherical spots), typically in a yellowish-green background. The name refers to the poppy-like look of the spots. Mindat treats Poppy Jasper as a synonym of Orbicular Jasper.

Prehnite is a natural calcium aluminium silicate mineral, Ca2Al2Si3O10(OH)2, usually pale green, yellowish green or yellow. It is mostly cut as translucent cabochons and beads; fully transparent material is extremely rare. Its Japanese and Chinese names, ぶどう石 and 葡萄石, mean "grape stone".

Purple tiger's eye is natural tiger's eye, a chatoyant variety of quartz, that has been dyed purple; it is a treated natural material, not a naturally purple variety. Gemological references describe natural tiger's eye in golden to brown tones and in blue (hawk's eye), and Gemdat and IGS state that it can be dyed to any colour. The Japanese retailer Pascle also states that its purple tiger's eye is artificially dyed.

Pyrite is a natural iron sulfide mineral (FeS₂) with a brass-yellow colour and bright metallic lustre, and is the most common sulfide mineral. Its gold-like appearance earned it the nickname "fool's gold". It is cut into beads, cabochons, faceted stones and carvings, and many stones sold as "marcasite" in jewellery are actually pyrite.

Rainbow fluorite is a trade name for natural fluorite (calcium fluoride, CaF₂) that shows two or more colors in one piece. The International Gem Society notes that lapidaries cut such multicolored gems from color-zoned crystals; fluorite crystals are frequently color zoned. Pascle, a Japanese retailer, uses the name for beads with several colors in one bead, most often green and purple, and notes it is also sold as "bicolor fluorite". It is the same mineral as other fluorite, not a separate species.

Red jasper is the red to reddish-brown form of jasper, a natural, opaque, impure microcrystalline (cryptocrystalline) quartz, SiO₂, usually grouped with chalcedony or chert. Its red color comes from abundant fine inclusions of hematite and other iron oxides or hydroxides. Mindat notes that red or brown is the historical core meaning of the name jasper.

Red tiger's eye is tiger's eye, a natural chatoyant variety of quartz, with a brownish-red to dark red colour that is normally the result of treatment. Gemdat (citing Lazzarelli) and IGS state that tiger's eye is heat-treated to develop red colours, and Gemdat calls the dark red heated material "bull's eye"; IGS also illustrates red cabochons that are dyed. The Japanese retailer Pascle likewise states that most red tiger's eye on the market is heated yellow tiger's eye.

Rhodolite is a natural purplish red garnet whose composition lies in the pyrope–almandine series. Mindat notes that the name originally meant a rose-red gem variety of pyrope but now covers pink to purplish garnets in that series, many of them closer to almandine. IGS stresses that the purplish red hue, not an exact recipe, defines rhodolite, and that small amounts of other garnet species are always present.

Rhyolite is a natural rock, not a single mineral: an extrusive (volcanic) igneous rock with a very high silica content, the fine-grained equivalent of granite. It is made up mainly of quartz and feldspar (alkali feldspar such as sanidine, and plagioclase), with minor hornblende and biotite, in grains usually too small to see without a hand lens. Rhyolites with flow banding or spherulites are the ones most used as gem rocks.

Rock crystal is the traditional name for clear, colourless quartz (silicon dioxide, SiO₂), a natural mineral. It is one variety of quartz, not a name for the whole quartz family: coloured varieties such as amethyst, citrine and rose quartz have their own names. Except for being colourless and clear, it has no property that other crystalline quartz lacks.

Ruby is the red variety of corundum (aluminium oxide), a natural mineral species that also includes sapphire. Pure corundum is colourless; ruby's red, ranging from orangy red to purplish red, is caused by traces of chromium, which can also cause red fluorescence. Corundum of any other colour is called sapphire.

Ruby in zoisite, also called anyolite, is a natural metamorphic rock rather than a single mineral: bright green chromium-bearing zoisite containing opaque purplish-red to pink ruby (corundum) crystals, often with black to very dark green amphibole (pargasite, also described as hornblende or tschermakite). It was first reported in 1954 near Longido, Tanzania, and is cut into cabochons, beads, carvings and small sculptures.

Sado red jasper, called akadama-ishi (赤玉石) in Japan, is a natural red jasper from the Akadama district on the southeastern coast of Sado Island, Niigata Prefecture. Sado City describes it as a very hard aggregate of tiny quartz crystals, also called ferruginous quartz (鉄石英), whose red color comes from hematite. The Sado Geopark counts it among Japan's three great named stones (日本三大銘石).

Sajigawa stone (Sajigawa-ishi) is a natural metamorphic rock from the Saji area of Tottori City, Tottori Prefecture: a dark, blackish-green rock derived from basaltic lava and pyroclastic rock of Paleozoic submarine volcanoes, belonging to the Sangun metamorphic belt. It is counted among Japan's three famous stones and is prized as a bonseki, garden stone and suiseki; collection has been prohibited since 1965.

Selenite is the transparent, crystalline variety of gypsum, a natural hydrous calcium sulfate mineral (CaSO₄·2H₂O); it contains no selenium. Mindat notes that the name is mostly synonymous with gypsum and has historically meant the transparent variety, as opposed to fibrous satin spar and fine-grained alabaster. White, silky material showing a cat's-eye band, such as the beads the Japanese retailer Pascle sells as selenite, matches the definition of satin spar gypsum rather than transparent selenite.

Smoky quartz is the grey, brown to black variety of quartz (SiO₂). Its colour comes from natural gamma irradiation acting on traces of aluminium built into the crystal lattice, which creates colour centres. Nearly black smoky quartz is called morion. Smoky quartz can also be produced by irradiating colourless quartz, and this is not detectable with standard tests.

Sodalite is a natural mineral, a sodium aluminium silicate with chlorine (Na₄Al₃Si₃O₁₂Cl) of the sodalite group, also classed as a feldspathoid; its name refers to its sodium content. As a gem it is usually massive, light to dark rich blue, often veined with white calcite. It belongs to the same mineral group as haüyne, lazurite and nosean, the blue minerals that principally make up the rock lapis lazuli, but sodalite itself is a single mineral.

Spectrolite is a locality and trade name for natural labradorite, a plagioclase feldspar, from the Ylämaa area of south-eastern Finland, where it occurs in a dark rock and shows unusually strong iridescence in the full range of spectral colors. The Geological Survey of Finland calls it the gemstone name of this rainbow-colored plagioclase feldspar, and Mindat lists it as a variety of labradorite. The name is also used for the dark spectrolite-bearing rock quarried as natural stone.

Spiderweb obsidian is a trade name for a brecciated obsidian, a natural volcanic glass broken into fragments, whose pattern of thin lines resembles a spider's web. It is natural rock, not a mineral and not man-made.

Sunstone is a feldspar gem material; its sparkling varieties contain reflective inclusions. Both orthoclase and plagioclase feldspars have sunstone varieties, so the name describes appearance rather than chemistry. Heliolite, sun stone and aventurine feldspar are alternate names.

Super Seven (also sold as Sacred Seven or Melody Stone) is a trade name, not a mineral name, for natural quartz, mostly amethyst and smoky quartz, that contains inclusions of other minerals. Sellers claim it holds seven minerals: amethyst, clear quartz, smoky quartz, rutile, goethite, lepidocrocite and cacoxenite. Three of these are colour varieties of quartz itself, and Mindat managers report that pieces on sale never showed all seven and that the "cacoxenite" and "lepidocrocite" were often really goethite and hematite.

Tanzanite is the transparent violet-blue to blue-violet variety of the natural mineral zoisite, a calcium aluminium silicate. It is mined commercially only in the Merelani Hills of northern Tanzania, after which Tiffany & Co. named it. Most tanzanite on the market has been heat treated to remove brownish or yellow-green tones and bring out its blue and violet colour.

Tourmalinated quartz is natural clear quartz containing needle- or rod-like crystals of tourmaline, usually black schorl. Long thin black needles in quartz are common and are often mistaken for rutile; the retailer Pascle notes that many stones sold as "black rutilated quartz" are in fact tourmalinated quartz.

Turquoise is a blue-to-green, hydrated copper and aluminum phosphate.

Unakite is a natural rock, not a single mineral: an altered granite made chiefly of pink orthoclase feldspar, green epidote and white to smoky quartz. The epidote formed secondarily, replacing the mica or hornblende of the original granitic rock. It takes a high polish and is used as an ornamental stone.

Variscite is a natural hydrated aluminium phosphate mineral (AlPO₄·2H₂O), usually yellowish green to bluish green and found as fine-grained nodules, veins and crusts. Gem material is cut into cabochons, beads and carvings and can closely resemble turquoise. It forms a series with the iron-dominant mineral strengite.

Verdite is a trade name for grayish green to bright green natural metamorphic rocks from southern Africa that owe their color to abundant fuchsite, a chromium-rich variety of muscovite mica. Its composition varies: some verdite is mostly fuchsite, some is fuchsite intergrown with other micas, and some is serpentine with enough fuchsite to turn it green. It is soft and is mainly used for carvings and decorative stone. The name comes from the Latin viridis, "green".

Yamanashi crystal is natural quartz (SiO₂) mined in Yamanashi Prefecture, Japan, mainly in the granite mountains around Mount Kinpu (Kinpusan). It is a locality name, not a separate mineral: the deposits yielded colourless rock crystal as well as white, smoky, chlorite-included and, rarely, amethyst quartz. Mining flourished in the Meiji era and has since ended; the largest mine, Otome, closed in 1981.

Yellow opal is natural common opal with a yellow body color and no play-of-color. Common opal is usually white, gray or brown, but traces of other substances can color it yellow, orange, green, blue or pink. Transparent to translucent yellow to red opal is also classed as fire opal, so the boundary between yellow common opal and yellow fire opal is not sharp. The Japanese retailer Pascle also calls it "banana opal".

Yellow tiger's eye is the classic golden-yellow to golden-brown tiger's eye: a natural, chatoyant variety of quartz. Parallel fibres of the amphibole crocidolite (a form of riebeckite) enclosed in the quartz have weathered to iron oxides and hydroxides, which give the golden colour and the moving band of light. Mindat lists pseudocrocidolite as a synonym, and South African mining studies separate this yellow type from blue (hawk's eye) and variegated tiger's eye.

Yellow tourmaline is a natural mineral: the yellow color range of tourmaline, a group of closely related borosilicate mineral species. The name does not fix one species. According to Gems & Gemology, the most important source of yellow gem elbaite is the Canary mining area in eastern Zambia, whose manganese-rich stones have been marketed as Canary tourmaline since 2001, while GIA notes that bright yellow "savannah" tourmalines are dravite–uvite mixtures colored by iron.