Random Gemstone Generator: Gems With Color, Hardness and Family

One press gives gemstones, each with its color, its Mohs hardness, what it is made of and its birthstone month if it has one.

Random Gemstone Generator: Gems With Color, Hardness and Family

  1. Sodalite
  2. Aquamarine
  3. Fluorite
  4. Iolite
  5. Ametrine
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Tip: the space bar makes new ones.

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Next step Draw a month, then find its birthstoneFind a color name for this stone

Random Gemstone Generator: Gems With Color, Hardness and Family: how it works

From diamond at 10 on the Mohs scale down to amber at 2, this list holds 90 gemstones. Each card gives the color, the hardness and the mineral the stone belongs to, and 39 carry a birthstone month. Draw five, or filter by color, hardness or birth month.

What the Mohs number tells you

Friedrich Mohs built the scale in 1812 from ten minerals, talc at 1 up to diamond at 10. A higher number scratches a lower one, and the steps are not even: diamond is about four times as hard as corundum. For a ring, watch for 7. Household dust contains quartz, so softer stones dull with daily wear, and 34 of the 90 never reach 7. Hardness is not toughness. A steel hammer cannot scratch a diamond but can shatter one, while softer jade is rated very tough.

One mineral, many gem names

Gem names follow color, not chemistry. Ruby and sapphire are both corundum: chromium turns it red, iron and titanium turn it blue. Emerald, aquamarine and morganite are all beryl. Draw 10 from the random gemstone generator and read the last line of each card: stones that look nothing alike turn out to be family.

Tips

  • Many stones on sale are treated. Most citrine is heated amethyst, and most blue topaz began colorless.
  • Classroom game: draw 5, tap Hide all facts, and have the class order the names from softest to hardest.
  • Story props: tap a color chip and draw 3. Pearl and amber suit a necklace. A sword hilt wants 7 or more.

Questions and answers

How are the 90 gemstones split by color?

90 gemstones: 20 red and pink, 24 orange, yellow and brown, 24 green, 24 blue and purple, and 19 black, white and clear. 13 are banded or two-tone, 13 flash, glow or change color, and 39 are birthstones. A stone of several colors, such as spinel, sits under each, so the chips add up to more than 90.

Which stones count as birthstones here?

The months follow GIA's birthstone pages. The list goes back to 1912, and spinel joined in 2016. When the birthstone is a whole group, every card in it carries the month, so all 7 garnets say January. Blue topaz carries none, because GIA's own pages disagree on whether it belongs to December. Pick June in the Birth month menu for its 5 stones.

Are all of these minerals?

No. Pearl, amber, jet, precious coral and ammolite were made by living things. Obsidian and moldavite are natural glass, and moldavite formed when a meteorite struck southern Germany about 15 million years ago. Lapis lazuli is a rock of several minerals, and opal has no crystal structure.

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All 90 gemstones

Red and pink 20

  • Alexandrite Green in daylight, red under a lamp. Mohs 8.5. Chrysoberyl with chromium. June birthstone.
  • Almandine garnet Deep red to purplish red. Mohs 7 to 7.5. The most common gem garnet. January birthstone.
  • Ammolite Red and green iridescence. Mohs 3.5 to 4.5. Fossil ammonite shell from Alberta.
  • Carnelian Orange to red-brown. Mohs 6.5 to 7. Chalcedony colored by iron oxide.
  • Fire opal Yellow, orange or red. Mohs 5 to 6.5. Opal from Mexico, often with no flashes. October birthstone.
  • Jasper Opaque, most often red. Mohs 6.5 to 7. Chalcedony reddened by iron.
  • Kunzite Pink to violet. Mohs 6.5 to 7. Spodumene, a lithium mineral. Sunlight can fade it.
  • Morganite Pink to orange-pink. Mohs 7.5 to 8. Beryl colored by manganese.
  • Padparadscha sapphire Pinkish orange. Mohs 9. Corundum named for the lotus blossom. September birthstone.
  • Precious coral Pale pink to deep red. Mohs 3.5. The hard skeleton of a sea coral.
  • Pyrope garnet Blood red. Mohs 7 to 7.5. The only garnet that is always red. January birthstone.
  • Red beryl Red. Mohs 7.5 to 8. A very rare beryl from Utah, colored by manganese.
  • Rhodochrosite Rose red with pale bands. Mohs 3.5 to 4. Manganese carbonate.
  • Rhodolite garnet Rose to purplish red. Mohs 7 to 7.5. Garnet, a pyrope and almandine mix. January birthstone.
  • Rhodonite Pink with black veins. Mohs 5.5 to 6.5. A manganese mineral.
  • Rose quartz Pale pink. Mohs 7. A variety of quartz.
  • Rubellite tourmaline Red to pinkish red. Mohs 7 to 7.5. Tourmaline. October birthstone.
  • Ruby Red. Mohs 9. Corundum colored by chromium. July birthstone.
  • Spinel Red, pink, blue, purple or black. Mohs 8. Magnesium aluminum oxide. August birthstone.
  • Watermelon tourmaline Pink inside, green outside. Mohs 7 to 7.5. Tourmaline in two colors. October birthstone.

Orange, yellow and brown 21

  • Agate Curved bands in many colors. Mohs 6.5 to 7. Banded chalcedony, a fine-grained quartz.
  • Amber Yellow to brown. Mohs 2 to 2.5. Fossil tree resin, not a mineral.
  • Ametrine Purple and yellow in one stone. Mohs 7. Quartz that is part amethyst, part citrine.
  • Boulder opal Color flashes in brown ironstone. Mohs 5 to 6.5. Opal from Queensland, Australia. October birthstone.
  • Cat's eye chrysoberyl Yellowish with one sharp band of light. Mohs 8.5. Chrysoberyl with fine needles inside.
  • Chrysoberyl Yellowish green. Mohs 8.5. Its own mineral, not a beryl.
  • Citrine Yellow to orange. Mohs 7. A variety of quartz. November birthstone.
  • Fancy color diamond Yellow, blue, green and more. Mohs 10. About one diamond in 10,000. April birthstone.
  • Fire agate Brown with rainbow flashes. Mohs 6.5 to 7. Chalcedony layered with iron oxide.
  • Heliodor Yellow to greenish yellow. Mohs 7.5 to 8. Golden beryl, colored by iron.
  • Hessonite garnet Yellow-red to red-orange. Mohs 6.5 to 7. Grossular garnet, the cinnamon stone. January birthstone.
  • Imperial topaz Golden to pinkish orange. Mohs 8. Topaz from Brazil. November birthstone.
  • Pyrite Brassy yellow metal. Mohs 6 to 6.5. Iron sulfide, known as fool's gold.
  • Sardonyx Brown-red bands with white or black. Mohs 6.5 to 7. Banded chalcedony. August birthstone.
  • Smoky quartz Gray-brown to black. Mohs 7. A variety of quartz.
  • South Sea pearl White to silver or golden. Mohs 2.5 to 3. Large pearl from the Pinctada maxima oyster. June birthstone.
  • Spessartine garnet Orange to yellow. Mohs 6.5 to 7.5. Garnet named for Spessart in Bavaria. January birthstone.
  • Sphene Yellow-green. Mohs 5 to 5.5. Titanite, with more fire than diamond.
  • Sunstone Orange to red with a metallic glitter. Mohs 6 to 7.2. Feldspar, the Oregon state gem.
  • Tiger's eye Golden to red-brown with a silky band of light. Mohs 6.5 to 7. Quartz with fine parallel fibers inside.
  • Zircon Blue, golden, red or colorless. Mohs 6 to 7.5. Zirconium silicate, not cubic zirconia. December birthstone.

Green 18

  • Amazonite Green to blue-green. Mohs 6 to 6.5. Feldspar, named for the Amazon River.
  • Apatite Green, blue or yellow. Mohs 5. Calcium phosphate, the mineral that marks 5 on the scale.
  • Bloodstone Dark green with red spots. Mohs 6.5 to 7. Chalcedony spotted with iron oxide. March birthstone.
  • Chrome diopside Rich green. Mohs 5.5 to 6.5. Diopside colored by chromium.
  • Chrysoprase Apple green. Mohs 6 to 7. Chalcedony colored by nickel.
  • Demantoid garnet Green. Mohs 6.5 to 7. Andradite garnet with more fire than diamond. January birthstone.
  • Emerald Green. Mohs 7.5 to 8. Beryl colored by chromium. May birthstone.
  • Fluorite Purple, blue, green or yellow. Mohs 4. Calcium fluoride, the mineral that marks 4 on the scale.
  • Jadeite Green, lavender or white. Mohs 6.5 to 7. A pyroxene, the rarer of the two jades.
  • Malachite Banded light and dark green. Mohs 3.5 to 4. A copper carbonate mineral.
  • Moldavite Forest green to olive green. Mohs 5.5 to 7. Natural glass made by a meteorite impact.
  • Moss agate Green moss-like patterns inside the stone. Mohs 6 to 7. Chalcedony, and not a true agate: it has no bands.
  • Nephrite Green to creamy white. Mohs 6 to 6.5. An amphibole, the tougher of the two jades.
  • Paraíba tourmaline Neon blue to green. Mohs 7 to 7.5. Tourmaline colored by copper. October birthstone.
  • Peridot Olive green. Mohs 6.5 to 7. Gem olivine, colored by iron. August birthstone.
  • Prasiolite Green. Mohs 7. A rare green quartz, most of it made by heating amethyst.
  • Tsavorite garnet Bright green. Mohs 6.5 to 7.5. Green grossular garnet, named for Tsavo. January birthstone.
  • Turquoise Sky blue to green. Mohs 5 to 6. Copper aluminum phosphate. December birthstone.

Blue and purple 15

  • Amethyst Purple. Mohs 7. A variety of quartz. February birthstone.
  • Aquamarine Blue to greenish blue. Mohs 7.5 to 8. Beryl colored by iron. March birthstone.
  • Azurite Deep blue. Mohs 3.5 to 4. A copper carbonate mineral, once ground for blue paint.
  • Benitoite Blue. Mohs 6 to 6.5. Barium titanium silicate, the California state gem.
  • Blue topaz Blue. Mohs 8. Topaz. Most began colorless and was treated to turn blue.
  • Charoite Swirling purple. Mohs 5 to 6. A mineral found only in the Sakha Republic, Siberia.
  • Indicolite tourmaline Light blue to bluish green. Mohs 7 to 7.5. Tourmaline. October birthstone.
  • Iolite Violet-blue, shifting as you turn it. Mohs 7 to 7.5. Gem cordierite.
  • Kyanite Blue. Mohs 4.5 to 5 along the crystal, 6.5 to 7 across it. Aluminum silicate.
  • Lapis lazuli Deep blue with gold flecks. Mohs 5 to 6. A rock: lazurite, calcite and pyrite.
  • Larimar Bluish white to deep blue. Mohs 4.5 to 5. Blue pectolite, found only in the Dominican Republic.
  • Sapphire Blue. Mohs 9. Corundum colored by iron and titanium. September birthstone.
  • Sodalite Royal blue with white veins. Mohs 5.5 to 6. Named for its sodium. Rarely has the pyrite of lapis.
  • Star sapphire Shows a six-rayed star of light. Mohs 9. Corundum with fine rutile needles. September birthstone.
  • Tanzanite Blue to violet. Mohs 6 to 7. Zoisite, mined only in Tanzania. December birthstone.

Black, white and clear 16

  • Black opal Dark body with bright flashes. Mohs 5 to 6.5. Opal from Lightning Ridge, Australia. October birthstone.
  • Diamond Colorless. Mohs 10. Pure carbon, the top of the scale. April birthstone.
  • Goshenite Colorless. Mohs 7.5 to 8. Pure beryl, named for Goshen, Massachusetts.
  • Hematite Metallic gray to black. Mohs 5.5 to 6.5. Iron oxide that leaves a red streak.
  • Howlite White with gray veins. Mohs 3.5. Often dyed blue to pass as turquoise.
  • Jet Black. Mohs 2.5 to 4. Fossil wood, and the jet in jet-black.
  • Labradorite Gray with flashes of blue and green. Mohs 6 to 6.5. Feldspar, first found in Labrador.
  • Moonstone Milky with a floating glow. Mohs 6 to 6.5. Feldspar in thin layers. June birthstone.
  • Obsidian Black. Mohs 5 to 6. Volcanic glass, not a mineral.
  • Onyx Black and white in straight bands. Mohs 6.5 to 7. Banded chalcedony.
  • Opal Flashes of every color. Mohs 5 to 6.5. Hydrated silica with no crystal structure. October birthstone.
  • Pearl Most often white or cream. Mohs 2.5 to 3. Nacre, laid down by a mollusk. June birthstone.
  • Rock crystal Colorless. Mohs 7. Pure, clear quartz.
  • Schorl (black tourmaline) Black. Mohs 7 to 7.5. The most common tourmaline in nature. October birthstone.
  • Snowflake obsidian Black with white snowflake spots. Mohs 5 to 6. Volcanic glass with cristobalite crystals.
  • Tahitian pearl Gray, black or brown. Mohs 2.5 to 3. Pearl from the black-lipped oyster. June birthstone.

How this list was compiled: 90 gemstones, written for this page. Mohs hardness, color and the cause of color come from the GIA Gem Encyclopedia, https://www.gia.edu/gem-encyclopedia, read one gem page at a time (for example https://www.gia.edu/opal and https://www.gia.edu/pearl), for the 29 gems GIA covers. Stones GIA does not cover use the infobox of their own Wikipedia article, found through https://en.wikipedia.org/wiki/List_of_gemstones_by_species. Where the two disagree the GIA figure is printed: opal 5 to 6.5, pearl 2.5 to 3, zircon 6 to 7.5, tanzanite 6 to 7, sunstone 6 to 7.2, spinel 8. Garnet species use their Wikipedia figures inside GIA's 6.5 to 7.5 for the group; tsavorite prints the group range because two Wikipedia articles differ. Neither GIA nor Wikipedia gives a figure for lapis lazuli, so its 5 to 6 is from the International Gem Society table at https://www.gemsociety.org/article/select-gems-ordered-mohs-hardness/, which was also used as a cross-check on the rest. Moss agate prints the 6 to 7 of chalcedony, https://en.wikipedia.org/wiki/Chalcedony, because its own article gives no figure. The ten reference minerals are from https://en.wikipedia.org/wiki/Mohs_scale. Birthstone months follow GIA's month pages, https://www.gia.edu/birthstones. When the birthstone is a whole species or group, every card in it carries the month: all garnets January, all sapphires September, all opals and tourmalines October, all pearls June, both diamonds April. Blue topaz carries no month because GIA's topaz page calls it a December stone and GIA's December page does not list it. What counts as a gemstone follows the USGS definition, any mineral or organic material used for adornment, at https://www.usgs.gov/centers/national-minerals-information-center/gemstones-statistics-and-information. Left out: ivory, on purpose; unakite, aventurine and mother of pearl, because no checked source gave a firm Mohs figure. x.mohs is the low end and x.mohsMax the high end of the printed range; the Hardness filter reads the low end, so 7 or more keeps a stone only when its whole range is 7 and up. All checked 2026-09-19. Licence: own work