Datasets:
name stringlengths 3 21 | species stringlengths 4 32 | family stringlengths 4 11 | formula stringlengths 1 40 | crystal_system stringlengths 5 27 | mohs_min float64 2 10 | mohs_max float64 2.5 10 | ri_min float64 1.37 2.42 ⌀ | ri_max float64 1.43 2.42 ⌀ | sg_min float64 1.08 4.32 | sg_max float64 1.08 4.73 | colors stringlengths 11 63 | verification stringclasses 4
values | notes stringlengths 40 258 ⌀ | sources stringlengths 24 123 | erebaur_url stringlengths 31 82 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Diamond | Diamond | diamond | C | cubic | 10 | 10 | 2.42 | 2.42 | 3.51 | 3.53 | colorless to yellow or brown; fancy colors | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/diamond/ |
Carbonado | Diamond | diamond | C | cubic (polycrystalline) | 10 | 10 | null | null | 2.8 | 3.45 | black, opaque | grade_a_with_exceptions | Mohs 10 is assigned as polycrystalline diamond, not measured. RI is empty because the material cannot be read on a refractometer. Only the density range comes from the GIA carbonado review (Gems & Gemology, Summer 2017). | https://www.gia.edu/gems-gemology/summer-2017-carbonado-diamond | https://erebaur.com/chapters/stones/?stone=Carbonado#fig-stone-table |
Ruby | Corundum | corundum | Al₂O₃ | trigonal | 9 | 9 | 1.762 | 1.77 | 3.95 | 4.05 | orangy red to purplish red | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/ruby/ |
Blue sapphire | Corundum | corundum | Al₂O₃ | trigonal | 9 | 9 | 1.762 | 1.77 | 3.95 | 4.05 | light to dark blue | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/blue-sapphire/ |
Padparadscha sapphire | Corundum | corundum | Al₂O₃ | trigonal | 9 | 9 | 1.762 | 1.77 | 3.95 | 4.05 | pinkish orange to orangy pink | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/padparadscha-sapphire/ |
Fancy sapphire | Corundum | corundum | Al₂O₃ | trigonal | 9 | 9 | 1.762 | 1.77 | 3.95 | 4.05 | violet, green, yellow, orange, pink, purple, parti-colored | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Fancy%20sapphire#fig-stone-table |
Emerald | Beryl | beryl | Be₃Al₂Si₆O₁₈ | hexagonal | 7.5 | 8 | 1.577 | 1.583 | 2.72 | 2.72 | green to bluish green | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/emerald/ |
Aquamarine | Beryl | beryl | Be₃Al₂Si₆O₁₈ | hexagonal | 7.5 | 8 | 1.577 | 1.583 | 2.72 | 2.72 | greenish blue, light in tone | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/aquamarine/ |
Morganite | Beryl | beryl | Be₃Al₂Si₆O₁₈ | hexagonal | 7.5 | 8 | 1.583 | 1.59 | 2.8 | 2.91 | pink to orange-pink | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/morganite/ |
Red beryl | Beryl | beryl | Be₃Al₂Si₆O₁₈ | hexagonal | 7.5 | 8 | 1.56 | 1.572 | 2.65 | 2.72 | raspberry to purplish red | grade_a_sourced | null | https://cms.gia.edu/dam/jcr:e7867d10-09cc-4122-839b-2bf053ea11f6/Winter-2003-Gems-Gemology-Red-Beryl-Utah-Review-Update.pdf | https://erebaur.com/chapters/stones/?stone=Red%20beryl#fig-stone-table |
Alexandrite | Chrysoberyl | chrysoberyl | BeAl₂O₄ | orthorhombic | 8.5 | 8.5 | 1.746 | 1.755 | 3.73 | 3.73 | bluish green in daylight, purplish red in incandescent light | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/alexandrite/ |
Pyrope | Pyrope | garnet | Mg₃Al₂(SiO₄)₃ | cubic | 6.5 | 7.5 | 1.714 | 1.742 | 3.582 | 3.582 | red, purplish red, orange-red | group_range | RI and SG are species-level values from Stockton and Manson (Gems & Gemology, Winter 1985), checked against the MSA Handbook of Mineralogy. The published RI maximum is an open bound (below 1.742), stored here as a plain value. Mohs is the garnet-group range. | https://www.gia.edu/gems-gemology/winter-1985-garnet-classification-stockton | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/stones/pyrope/ |
Almandine | Almandine | garnet | Fe₃Al₂(SiO₄)₃ | cubic | 6.5 | 7.5 | 1.785 | 1.83 | 4.318 | 4.318 | deep red, brownish red, violet red | group_range | RI and SG are species-level values from Stockton and Manson (Gems & Gemology, Winter 1985), checked against the MSA Handbook of Mineralogy. Mohs is the garnet-group range. | https://www.gia.edu/gems-gemology/winter-1985-garnet-classification-stockton | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Almandine#fig-stone-table |
Spessartine | Spessartine | garnet | Mn₃Al₂(SiO₄)₃ | cubic | 6.5 | 7.5 | 1.78 | 1.81 | 4.19 | 4.19 | light orange to reddish brown | group_range | RI and SG are species-level values from Stockton and Manson (Gems & Gemology, Winter 1985), checked against the MSA Handbook of Mineralogy. The published RI maximum is an open bound (below 1.810), stored here as a plain value. Mohs is the garnet-group range. | https://www.gia.edu/gems-gemology/winter-1985-garnet-classification-stockton | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Spessartine#fig-stone-table |
Tsavorite | Grossular | garnet | Ca₃Al₂(SiO₄)₃ | cubic | 7 | 7 | 1.739 | 1.744 | 3.57 | 3.65 | light to intense green | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Tsavorite#fig-stone-table |
Hessonite | Grossular | garnet | Ca₃Al₂(SiO₄)₃ | cubic | 7 | 7 | 1.731 | 1.76 | 3.4 | 3.78 | orange to cinnamon brown | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Hessonite#fig-stone-table |
Demantoid | Andradite | garnet | Ca₃Fe₂(SiO₄)₃ | cubic | 6.5 | 6.5 | 1.88 | 1.889 | 3.8 | 3.88 | yellowish green to green | grade_a_sourced | null | https://www.gia.edu/dam/migrated-assets/docs/doc1/Russian-Demantoid-Czar-of-the-Garnet-Family.pdf | https://erebaur.com/stones/demantoid/ |
Rubellite | Elbaite | tourmaline | Na(Li₁.₅,Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄ | trigonal | 7 | 7.5 | 1.624 | 1.644 | 3 | 3.26 | pink, red, purplish red, orangy red, brownish red | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Rubellite#fig-stone-table |
Indicolite | Elbaite | tourmaline | Na(Li₁.₅,Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄ | trigonal | 7 | 7.5 | 1.624 | 1.644 | 3 | 3.26 | dark violetish blue, blue, greenish blue | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Indicolite#fig-stone-table |
Paraíba tourmaline | Elbaite | tourmaline | Na(Li₁.₅,Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄ | trigonal | 7 | 7.5 | 1.624 | 1.644 | 3 | 3.26 | intense violetish blue, greenish blue, blue | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/paraiba-tourmaline/ |
Red spinel | Spinel | spinel | MgAl₂O₄ | cubic | 8 | 8 | 1.718 | 1.718 | 3.6 | 3.6 | red to pink (chromium) | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/red-spinel/ |
Cobalt blue spinel | Spinel | spinel | MgAl₂O₄ | cubic | 8 | 8 | 1.718 | 1.718 | 3.6 | 3.6 | saturated blue (cobalt) | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Cobalt%20blue%20spinel#fig-stone-table |
Amethyst | Quartz | quartz | SiO₂ | trigonal | 7 | 7 | 1.544 | 1.553 | 2.64 | 2.69 | light lilac to deep purple, often zoned | grade_a_sourced | Chapter 03 flags 1.544, the quartz RI used in its dispersion chart, as not confirmed on a fetched grade-A page. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/amethyst/ |
Citrine | Quartz | quartz | SiO₂ | trigonal | 7 | 7 | 1.544 | 1.553 | 2.64 | 2.69 | yellow to orange to orangy red | grade_a_sourced | Chapter 03 flags 1.544, the quartz RI used in its dispersion chart, as not confirmed on a fetched grade-A page. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/citrine/ |
Rose quartz | Quartz | quartz | SiO₂ | trigonal | 7 | 7 | 1.544 | 1.553 | 2.64 | 2.69 | very light to medium-dark pink | grade_a_sourced | Chapter 03 flags 1.544, the quartz RI used in its dispersion chart, as not confirmed on a fetched grade-A page. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Rose%20quartz#fig-stone-table |
Smoky quartz | Quartz | quartz | SiO₂ | trigonal | 7 | 7 | 1.544 | 1.553 | 2.64 | 2.69 | light brown to black | grade_a_sourced | Chapter 03 flags 1.544, the quartz RI used in its dispersion chart, as not confirmed on a fetched grade-A page. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Smoky%20quartz#fig-stone-table |
Agate | Quartz (chalcedony) | quartz | SiO₂ | trigonal (microcrystalline) | 6.5 | 7 | 1.535 | 1.539 | 2.6 | 2.6 | banded, many colors | unverified_secondary_source | No grade-A source found. RI, SG and Mohs come from the International Gem Society, The Gemology Project or Wikipedia and should be re-measured or re-sourced. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/agate/ |
Chrysoprase | Quartz (chalcedony) | quartz | SiO₂ | trigonal (microcrystalline) | 6.5 | 7 | 1.535 | 1.539 | 2.6 | 2.6 | apple green | unverified_secondary_source | No grade-A source found. RI, SG and Mohs come from the International Gem Society, The Gemology Project or Wikipedia and should be re-measured or re-sourced. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Chrysoprase#fig-stone-table |
Precious opal | Opal | opal | SiO₂·nH₂O | amorphous | 5 | 6.5 | 1.37 | 1.47 | 1.25 | 2.23 | white, gray or black body with play-of-color | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/precious-opal/ |
Jadeite | Jadeite | jade | NaAlSi₂O₆ | monoclinic (aggregate) | 6.5 | 7 | 1.666 | 1.68 | 3.34 | 3.34 | green, white, yellow, reddish orange, lavender, gray, black | grade_a_sourced | null | https://www.gia.edu/jade | https://erebaur.com/stones/jadeite/ |
Nephrite | Actinolite-tremolite | jade | Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂ | monoclinic (aggregate) | 6 | 6.5 | 1.606 | 1.632 | 2.95 | 2.95 | light to dark green, yellow, brown, black, gray, white | grade_a_sourced | null | https://www.gia.edu/jade | https://erebaur.com/stones/nephrite/ |
Tanzanite | Zoisite | other | Ca₂Al₃(SiO₄)₃(OH) | orthorhombic | 6 | 7 | 1.691 | 1.7 | 3.35 | 3.35 | violet blue to bluish violet to violet purple | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/tanzanite/ |
Topaz | Topaz | other | Al₂SiO₄(F,OH)₂ | orthorhombic | 8 | 8 | 1.619 | 1.627 | 3.53 | 3.53 | yellow, orange, brown, pink to red to purple, blue, colorless | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/topaz/ |
Zircon | Zircon | other | ZrSiO₄ | tetragonal | 6 | 7.5 | 1.81 | 1.984 | 3.9 | 4.73 | blue, red, yellow, orange, brown, green | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/zircon/ |
Peridot | Olivine | other | (Mg,Fe)₂SiO₄ | orthorhombic | 6.5 | 7 | 1.65 | 1.69 | 3.34 | 3.34 | brown-green to yellowish green to pure green | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/peridot/ |
Iolite | Cordierite | other | Mg₂Al₄Si₅O₁₈ | orthorhombic | 7 | 7.5 | 1.542 | 1.551 | 2.61 | 2.61 | violetish blue (pleochroic to colorless-yellow) | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/chapters/stones/?stone=Iolite#fig-stone-table |
Kunzite | Spodumene | other | LiAlSi₂O₆ | monoclinic | 6.5 | 7 | 1.66 | 1.676 | 3.18 | 3.18 | pink to violetish purple | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/kunzite/ |
Turquoise | Turquoise | other | CuAl₆(PO₄)₄(OH)₈·4H₂O | triclinic | 5 | 6 | 1.61 | 1.65 | 2.4 | 2.9 | blue to green | grade_a_sourced | The formula is the IMA-CNMNC one, with four waters. GIA writes it with five. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/turquoise/ |
Lapis lazuli | Rock (lazurite, calcite, pyrite) | other | Lazurite: Na₇Ca(Al₆Si₆O₂₄)(SO₄)(S₃)⁻·H₂O | rock (lazurite cubic) | 5 | 6 | 1.5 | 1.67 | 2.5 | 3 | greenish blue to violetish blue, with calcite and pyrite | grade_a_with_exceptions | Mohs (5–6) has no grade-A source; RI and SG are GIA’s. The formula is the IMA-CNMNC lazurite formula from redefinition proposal 20-H. | https://www.gia.edu/gem-encyclopedia | https://erebaur.com/stones/lapis-lazuli/ |
Malachite | Malachite | other | Cu₂CO₃(OH)₂ | monoclinic | 3.5 | 4.5 | 1.655 | 1.909 | 3.6 | 4.05 | light to dark green, banded | grade_a_sourced | Values follow the MSA Handbook of Mineralogy. | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Malachite#fig-stone-table |
Moonstone | Orthoclase | other | KAlSi₃O₈ | monoclinic | 6 | 6.5 | 1.518 | 1.526 | 2.58 | 2.58 | colorless to white, gray, green, peach, brown; blue sheen | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/moonstone/ |
Labradorite | Plagioclase | other | (Ca,Na)(Al,Si)₄O₈ | triclinic | 6 | 6.5 | 1.559 | 1.568 | 2.7 | 2.7 | gray to dark with blue, green, gold flash | grade_a_sourced | Mohs 6–6.5 follows the MSA Handbook of Mineralogy for plagioclase. GIA’s own feldspar pages disagree with each other on hardness. | https://handbookofmineralogy.org/pdfs/labradorite.pdf | https://erebaur.com/chapters/stones/?stone=Labradorite#fig-stone-table |
Sunstone (oligoclase) | Plagioclase | other | (Na,Ca)(Al,Si)₄O₈ | triclinic | 6 | 6.5 | 1.537 | 1.547 | 2.65 | 2.65 | yellow, green, red, red-brown, colorless, with glitter | grade_a_sourced | Mohs 6–6.5 follows the MSA Handbook of Mineralogy for plagioclase. GIA’s own feldspar pages disagree with each other on hardness. | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Sunstone%20(oligoclase)#fig-stone-table |
Apatite | Apatite | other | Ca₅(PO₄)₃(F,OH,Cl) | hexagonal | 5 | 5 | 1.628 | 1.649 | 3.1 | 3.35 | blue-green, green, yellow, violet, pink | grade_a_sourced | Values follow the MSA Handbook of Mineralogy (fluorapatite). | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Apatite#fig-stone-table |
Sphene | Titanite | other | CaTiSiO₅ | monoclinic | 5 | 5.5 | 1.843 | 2.11 | 3.45 | 3.55 | yellow, green, brown | grade_a_sourced | Values follow the MSA Handbook of Mineralogy (titanite). | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Sphene#fig-stone-table |
Andalusite | Andalusite | other | Al₂SiO₅ | orthorhombic | 6.5 | 7.5 | 1.627 | 1.649 | 3.13 | 3.17 | green to reddish brown (pleochroic) | grade_a_sourced | Values follow the MSA Handbook of Mineralogy. | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Andalusite#fig-stone-table |
Kyanite | Kyanite | other | Al₂SiO₅ | triclinic | 5.5 | 7 | 1.71 | 1.734 | 3.53 | 3.68 | blue, blue-green, green, orange | grade_a_sourced | Hardness is directional: 5.5 parallel to [001] and 7 parallel to [100] (MSA Handbook of Mineralogy). | https://handbookofmineralogy.org/pdfs/kyanite.pdf | https://erebaur.com/chapters/stones/?stone=Kyanite#fig-stone-table |
Chrome diopside | Diopside | other | CaMgSi₂O₆ | monoclinic | 5.5 | 6.5 | 1.664 | 1.73 | 3.22 | 3.38 | intense green | grade_a_sourced | Values follow the MSA Handbook of Mineralogy (diopside). | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/stones/chrome-diopside/ |
Fluorite | Fluorite | other | CaF₂ | cubic | 4 | 4 | 1.432 | 1.434 | 3.18 | 3.18 | purple, green, blue, yellow, colorless | grade_a_sourced | Values follow the MSA Handbook of Mineralogy. Chapter 03 flags 1.434, the fluorite RI used in its dispersion chart, as not confirmed on a fetched grade-A page. | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Fluorite#fig-stone-table |
Painite | Painite | rare | CaZrAl₉O₁₅(BO₃) | hexagonal | 7.5 | 8 | 1.787 | 1.816 | 4.01 | 4.01 | red, brownish red, orange-red | grade_a_sourced | Values follow the MSA Handbook of Mineralogy. | https://handbookofmineralogy.org/pdf-search/ | https://www.gia.edu/dam/migrated-assets/gems-and-gemology/pdf/WN05.pdf | https://erebaur.com/chapters/stones/?stone=Painite#fig-stone-table |
Taaffeite | Taaffeite | rare | BeMg₃Al₈O₁₆ | hexagonal | 8 | 8.5 | 1.716 | 1.728 | 3.61 | 3.67 | mauve to purple, purplish red, grayish violet, colorless | grade_a_with_exceptions | RI and SG come from a study of ten stones, eight of them chromium-bearing, so the range may be narrower than the species. Mohs (8–8.5) is a trade figure with no grade-A source. | https://www.gia.edu/dam/jcr:4b5d009c-53ed-464a-a8cd-4d5ab23f56c6/SP00.pdf | https://erebaur.com/chapters/stones/?stone=Taaffeite#fig-stone-table |
Grandidierite | Grandidierite | rare | MgAl₃BSiO₉ | orthorhombic | 7 | 7.5 | 1.583 | 1.622 | 2.94 | 2.98 | greenish blue to blue-green | grade_a_with_exceptions | RI and SG come from the first faceted stone from Sri Lanka. A later GIA study of Madagascar material gives a density near 3.01, so SG may be low. Mohs has no grade-A source. | https://www.gia.edu/dam/migrated-assets/gems-and-gemology/pdf/SP03.pdf | https://erebaur.com/chapters/stones/?stone=Grandidierite#fig-stone-table |
Benitoite | Benitoite | rare | BaTiSi₃O₉ | hexagonal | 6 | 6.5 | 1.757 | 1.805 | 3.65 | 3.68 | violetish blue, colorless, rarely pink | grade_a_sourced | Chapter 03 flags 1.757, the benitoite RI used in its dispersion chart, as not confirmed on a fetched grade-A page. | https://www.gia.edu/dam/migrated-assets/gems-and-gemology/pdf/FA97.pdf | https://erebaur.com/chapters/stones/?stone=Benitoite#fig-stone-table |
Jeremejevite | Jeremejevite | rare | Al₆B₅O₁₅(F,OH)₃ | hexagonal | 6.5 | 7.5 | 1.637 | 1.653 | 3.28 | 3.31 | colorless, pale blue, blue, yellow | grade_a_sourced | Values follow the MSA Handbook of Mineralogy. | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Jeremejevite#fig-stone-table |
Poudretteite | Poudretteite | rare | KNa₂B₃Si₁₂O₃₀ | hexagonal | 5 | 5 | 1.511 | 1.532 | 2.51 | 2.53 | colorless to pale pink, purple-pink | grade_a_sourced | null | https://www.gia.edu/dam/migrated-assets/gems-and-gemology/pdf/SP03.pdf | https://erebaur.com/chapters/stones/?stone=Poudretteite#fig-stone-table |
Serendibite | Serendibite | rare | Ca₂(Mg,Al)₆(Si,Al,B)₆O₂₀ | triclinic | 6.5 | 7 | 1.701 | 1.706 | 3.42 | 3.52 | grayish blue, blue-green, black | grade_a_sourced | Values follow the MSA Handbook of Mineralogy. | https://handbookofmineralogy.org/pdf-search/ | https://erebaur.com/chapters/stones/?stone=Serendibite#fig-stone-table |
Pearl | Nacre (calcium carbonate) | organic | CaCO₃ | organic | 2.5 | 3 | 1.52 | 1.69 | 2.6 | 2.85 | white, black, gray, yellow, orange, pink, lavender, green, blue | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/pearl/ |
Amber | Fossil resin | organic | C₁₀H₁₆O | organic | 2 | 2.5 | 1.54 | 1.54 | 1.08 | 1.08 | yellow, orange, brown; rarely blue or green | grade_a_sourced | null | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/amber/ |
Precious coral | Coralliidae skeleton | organic | CaCO₃ (calcite) | organic | 3.5 | 3.5 | 1.486 | 1.658 | 2.8 | 2.8 | white, pink, salmon, red | grade_a_sourced | Values follow CIBJO’s Coral Book (2024). | https://cibjo.org/wp-content/uploads/2024/11/November-2024-Coral-Blue-Book.pdf | https://erebaur.com/stones/precious-coral/ |
Jet | Lignite | organic | C with impurities | organic | 2.5 | 4 | 1.66 | 1.66 | 1.19 | 1.35 | black to dark brown | unverified_secondary_source | No grade-A source found. RI, SG and Mohs come from the International Gem Society, The Gemology Project or Wikipedia and should be re-measured or re-sourced. | https://erebaur.com/chapters/stones/#sources | https://erebaur.com/stones/jet/ |
Erebaur Gem Properties
Physical and optical properties of 60 gem materials: species, chemical formula, crystal system, Mohs hardness, refractive index, specific gravity and colors, with a verification status for every row. From the property table in Chapter 02 of the Erebaur encyclopedia.
60 rows, one CSV file: gem-properties.csv (UTF-8, comma-separated, header row).
Attribution
Required wherever the data is reused:
Data: Erebaur (https://erebaur.com), CC BY 4.0
The link goes to the matching page on the site, https://erebaur.com/stones/. Keep it when you reproduce the line.
Data dictionary
| Column | Type | Description |
|---|---|---|
name |
string | Stone or variety name as used in the encyclopedia. |
species |
string | Mineral species, or the material for rocks and organics. |
family |
string | Grouping used by the site’s filters: diamond, corundum, beryl, chrysoberyl, garnet, tourmaline, spinel, quartz, opal, jade, other, rare or organic. |
formula |
string | Chemical formula, with Unicode subscripts. |
crystal_system |
string | Crystal system, following the MSA Handbook of Mineralogy. Qualifiers in brackets mark aggregates and microcrystalline material. |
mohs_min |
numeric | Mohs hardness, low end of the range. |
mohs_max |
numeric | Mohs hardness, high end of the range. Equal to mohs_min when a single value is given. |
ri_min |
numeric | Refractive index, low end. Empty when the material cannot be read on a refractometer. |
ri_max |
numeric | Refractive index, high end. |
sg_min |
numeric | Specific gravity, low end. |
sg_max |
numeric | Specific gravity, high end. |
colors |
string | Colors the stone occurs in, as described in the encyclopedia. |
verification |
string | grade_a_sourced: values from GIA, Gems & Gemology, the MSA Handbook of Mineralogy or CIBJO. grade_a_with_exceptions: grade-A values except for the field named in notes. group_range: Mohs is the range for the whole garnet group rather than the species. unverified_secondary_source: no grade-A source found; values from secondary compilations. |
notes |
string | What Erebaur’s editorial review records about this row specifically. Empty when it records nothing. |
sources |
string | Sources in Chapter 02’s list that are about this stone or that the editorial review ties to this row, separated by " | ". Not a field-by-field citation. Otherwise the URL of the chapter’s full source list. |
erebaur_url |
url | The stone’s own page on erebaur.com, or its row in the chapter’s property table when it has none. |
Sources and how they were checked
Every row was checked in September 2026 against institutional sources only: the GIA Gem Encyclopedia and Gems & Gemology for each stone they cover, the Mineralogical Society of America’s Handbook of Mineralogy for minerals GIA does not profile, and CIBJO’s Coral Book for precious coral. No row is taken from Wikipedia except the three marked unverified_secondary_source, which still carry values from secondary compilations because no grade-A figure could be found.
Crystal systems follow the MSA Handbook of Mineralogy: GIA’s property boxes do not state them and the IMA-CNMNC list does not publish them. Where a property is given as a single value, *_min and *_max are equal.
The verification and notes columns restate Erebaur’s editorial review items for Chapter 02 and Chapter 03 (the chapter’s flags, listed in the site’s REVIEW.md). The generator checks each note against the review item it restates and refuses to run when one has changed.
The full source list for the chapter, as published on the site: https://erebaur.com/chapters/stones/#sources
- GIA Gem Encyclopedia: gem pages carrying species, Mohs hardness, refractive index, specific gravity and color
- GIA Gem Encyclopedia: Jade (jadeite, nephrite and green omphacite)
- GIA Gems & Gemology, Spring 2000: Burmese Jade, The Inscrutable Gem (Hughes); Chromium-Bearing Taaffeites (Schmetzer)
- GIA Gems & Gemology, Summer 1996: Russian Demantoid (Phillips and Talantsev), with calcium garnet property table
- GIA Gems & Gemology, Winter 2003: Red Beryl from Utah, A Review and Update (Shigley and others)
- GIA Gems & Gemology, Spring 2003: Poudretteite from the Mogok Valley; The First Transparent Faceted Grandidierite
- GIA Gems & Gemology, Fall 1997: Benitoite from the New Idria District, San Benito County, California (Laurs and others)
- GIA Gems & Gemology, Winter 2005, Gem News International: New discoveries of painite in Myanmar (Rossman)
- GIA Gems & Gemology, Summer 2009: The “Type” Classification System of Diamonds and Its Importance in Gemology (Breeding and Shigley)
- GIA Gems & Gemology, Summer 2017: Carbonado Diamond, A Review of Properties and Origin
- CIBJO Blue Book: The Gemstone Book, Coloured Stone Commission (2022), commercial names and treatment disclosure
- CITES species listing: Loxodonta africana (African elephant), Appendix I from 18 January 1990
- CITES AC31 Doc. 23: listing status and management of precious corals (Coralliidae and Antipatharia)
- US eCFR, 50 CFR 17.40(e): African elephant rule, prohibitions and de minimis and antique exceptions
- Mineralogical Society of America, Handbook of Mineralogy: PDF search index for the per-mineral data sheets (system, hardness, RI, density)
- GIA Gems & Gemology, Winter 1985: Stockton and Manson, A Proposed New Classification for Gem-Quality Garnets (Table 1)
- CIBJO Blue Book: The Coral Book, Coral Commission (November 2024), coral hardness, density and nomenclature
- GIA Gems & Gemology, Winter 1987: Fritsch and Misiorowski, The history and gemology of queen conch pearls
- GIA Gems & Gemology, Summer 2015, Gem News International: non-bead cultured pearls from Strombus gigas (queen conch)
- Sanders, Colour of precious opal, Nature 204 (1964) 1151–1153 (diffraction by ordered silica spheres)
- MSA Handbook of Mineralogy: Kyanite data sheet (hardness 5.5 parallel [001], 7 parallel [100])
- MSA Handbook of Mineralogy: Labradorite data sheet (hardness 6 to 6.5, density 2.68 to 2.72)
Known limitations
- Counts by verification status: grade_a_sourced 50, grade_a_with_exceptions 4, group_range 3, unverified_secondary_source 3.
- Ranges are gemmological ranges for the material as it is traded, not absolute limits for the mineral species.
- Some varieties carry their species’ ranges unchanged, so these columns cannot tell them apart: Ruby, Blue sapphire, Padparadscha sapphire, Fancy sapphire; Emerald, Aquamarine; Rubellite, Indicolite, Paraíba tourmaline; Red spinel, Cobalt blue spinel; Amethyst, Citrine, Rose quartz, Smoky quartz; Agate, Chrysoprase.
- Two published RI maxima are open bounds ("below 1.742" for pyrope, "below 1.810" for spessartine) stored as plain values.
- Taaffeite’s RI and SG come from a ten-stone study and may be narrower than the species; musgravite is absent because published RI and SG disagree.
- The table does not distinguish rhombohedral (a lattice system) from trigonal (a crystal system); see Chapter 03’s review items.
- Sphene’s dispersion of 0.051 and most dispersion values in Chapter 03 have no grade-A source. Dispersion is not a column here.
License
CC BY 4.0. The license covers Erebaur’s compilation: the selection and arrangement of the rows, the column structure and the descriptive text Erebaur wrote. The underlying facts are not owned by anyone, and the publications listed above keep their own rights. See ../LICENSE.
Citation
Data: Erebaur (https://erebaur.com), CC BY 4.0. Erebaur Gem Properties, compiled from the Erebaur encyclopedia, last reviewed 2026-09-19. https://erebaur.com/stones/
A machine-readable citation is in CITATION.cff.
Regenerating
These files are generated from the encyclopedia content. Do not edit them by hand: run npm run datasets in the site repository.
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