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60 stones, one register.

Every stone in the encyclopedia with its species, hardness, refractive index, density and colors. Pick one to read its record, then brief us if you want it found.

Properties table Chapter 02 · The stones
Stones
60
Species
44
Properties
Mohs · RI · SG
Source
Chapter 02
(Fig. 01)Species sheet60 stones · 6 classes

A cadastre
of gem species.

Each parcel is one stone from the reference table, grouped with its family like plots in a land register. Select a parcel to read its record.

COL ACOL BCOL CCOL DCOL EROW 1ROW 2ROW 3JadeiteNephriteAlexandriteCitrineApatiteCarbonadoRose quartzDiamondRed berylPrecious opalSmoky quartzParaíba tourmalineCobalt blue spinelRed spinelLapis lazuliFancy sapphireBlue sapphireRubyTsavoriteSpessartinePadparadscha sapphireRubellitePearlPrecious coralAmberBenitoiteN
(Fig. 02)Properties60 rows · sortable

The numbers
behind each stone.

Filter by family, search by name, sort by any column. Ranges show the spread a laboratory would accept for the species.

Fig. 02.1

Gem properties at a glance

60 rows

DiamondDiamondCcubic102.423.51–3.53colorless to yellow or brown; fancy colors
CarbonadoDiamondCcubic (polycrystalline)10–2.8–3.45black, opaque
RubyCorundumAl₂O₃trigonal91.762–1.773.95–4.05orangy red to purplish red
Blue sapphireCorundumAl₂O₃trigonal91.762–1.773.95–4.05light to dark blue
Padparadscha sapphireCorundumAl₂O₃trigonal91.762–1.773.95–4.05pinkish orange to orangy pink
Fancy sapphireCorundumAl₂O₃trigonal91.762–1.773.95–4.05violet, green, yellow, orange, pink, purple, parti-colored
EmeraldBerylBe₃Al₂Si₆O₁₈hexagonal7.5–81.577–1.5832.72green to bluish green
AquamarineBerylBe₃Al₂Si₆O₁₈hexagonal7.5–81.577–1.5832.72greenish blue, light in tone
MorganiteBerylBe₃Al₂Si₆O₁₈hexagonal7.5–81.583–1.592.8–2.91pink to orange-pink
Red berylBerylBe₃Al₂Si₆O₁₈hexagonal7.5–81.56–1.5722.65–2.72raspberry to purplish red
AlexandriteChrysoberylBeAl₂O₄orthorhombic8.51.746–1.7553.73bluish green in daylight, purplish red in incandescent light
PyropePyropeMg₃Al₂(SiO₄)₃cubic6.5–7.51.714–1.8883.47–4.15red, purplish red, orange-red
AlmandineAlmandineFe₃Al₂(SiO₄)₃cubic6.5–7.51.714–1.8883.47–4.15deep red, brownish red, violet red
SpessartineSpessartineMn₃Al₂(SiO₄)₃cubic6.5–7.51.714–1.8883.47–4.15light orange to reddish brown
TsavoriteGrossularCa₃Al₂(SiO₄)₃cubic71.739–1.7443.57–3.65light to intense green
HessoniteGrossularCa₃Al₂(SiO₄)₃cubic71.731–1.763.4–3.78orange to cinnamon brown
DemantoidAndraditeCa₃Fe₂(SiO₄)₃cubic6.51.88–1.8893.8–3.88yellowish green to green
RubelliteElbaiteNa(Li₁.₅,Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄trigonal7–7.51.624–1.6443–3.26pink, red, purplish red, orangy red, brownish red
IndicoliteElbaiteNa(Li₁.₅,Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄trigonal7–7.51.624–1.6443–3.26dark violetish blue, blue, greenish blue
Paraíba tourmalineElbaiteNa(Li₁.₅,Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄trigonal7–7.51.624–1.6443–3.26intense violetish blue, greenish blue, blue
Red spinelSpinelMgAl₂O₄cubic81.7183.6red to pink (chromium)
Cobalt blue spinelSpinelMgAl₂O₄cubic81.7183.6saturated blue (cobalt)
AmethystQuartzSiO₂trigonal71.544–1.5532.64–2.69light lilac to deep purple, often zoned
CitrineQuartzSiO₂trigonal71.544–1.5532.64–2.69yellow to orange to orangy red
Rose quartzQuartzSiO₂trigonal71.544–1.5532.64–2.69very light to medium-dark pink
Smoky quartzQuartzSiO₂trigonal71.544–1.5532.64–2.69light brown to black
AgateQuartz (chalcedony)SiO₂trigonal (microcrystalline)6.5–71.535–1.5392.6banded, many colors
ChrysopraseQuartz (chalcedony)SiO₂trigonal (microcrystalline)6.5–71.535–1.5392.6apple green
Precious opalOpalSiO₂·nH₂Oamorphous5–6.51.37–1.471.25–2.23white, gray or black body with play-of-color
JadeiteJadeiteNaAlSi₂O₆monoclinic (aggregate)6.5–71.666–1.683.34green, white, yellow, reddish orange, lavender, gray, black
NephriteActinolite-tremoliteCa₂(Mg,Fe)₅Si₈O₂₂(OH)₂monoclinic (aggregate)6–6.51.606–1.6322.95light to dark green, yellow, brown, black, gray, white
TanzaniteZoisiteCa₂Al₃(SiO₄)₃(OH)orthorhombic6–71.691–1.73.35violet blue to bluish violet to violet purple
TopazTopazAl₂SiO₄(F,OH)₂orthorhombic81.619–1.6273.53yellow, orange, brown, pink to red to purple, blue, colorless
ZirconZirconZrSiO₄tetragonal6–7.51.81–1.9843.9–4.73blue, red, yellow, orange, brown, green
PeridotOlivine(Mg,Fe)₂SiO₄orthorhombic6.5–71.65–1.693.34brown-green to yellowish green to pure green
IoliteCordieriteMg₂Al₄Si₅O₁₈orthorhombic7–7.51.542–1.5512.61violetish blue (pleochroic to colorless-yellow)
KunziteSpodumeneLiAlSi₂O₆monoclinic6.5–71.66–1.6763.18pink to violetish purple
TurquoiseTurquoiseCuAl₆(PO₄)₄(OH)₈·5H₂Otriclinic5–61.61–1.652.4–2.9blue to green
Lapis lazuliRock (lazurite, calcite, pyrite)Lazurite: (Na,Ca)₈(Al,Si)₁₂O₂₄(S,SO₄)rock (lazurite cubic)5–61.5–1.672.5–3greenish blue to violetish blue, with calcite and pyrite
MalachiteMalachiteCu₂CO₃(OH)₂monoclinic3.5–4.51.655–1.9093.6–4.05light to dark green, banded
MoonstoneOrthoclaseKAlSi₃O₈monoclinic6–6.51.518–1.5262.58colorless to white, gray, green, peach, brown; blue sheen
LabradoritePlagioclase(Ca,Na)(Al,Si)₄O₈triclinic6–7.21.559–1.5682.7gray to dark with blue, green, gold flash
Sunstone (oligoclase)Plagioclase(Na,Ca)(Al,Si)₄O₈triclinic6–7.21.537–1.5472.65yellow, green, red, red-brown, colorless, with glitter
ApatiteApatiteCa₅(PO₄)₃(F,OH,Cl)hexagonal51.628–1.6493.1–3.35blue-green, green, yellow, violet, pink
SpheneTitaniteCaTiSiO₅monoclinic5–5.51.843–2.113.45–3.55yellow, green, brown
AndalusiteAndalusiteAl₂SiO₅orthorhombic6.5–7.51.627–1.6493.13–3.17green to reddish brown (pleochroic)
KyaniteKyaniteAl₂SiO₅triclinic4–7.51.71–1.7343.53–3.68blue, blue-green, green, orange
Chrome diopsideDiopsideCaMgSi₂O₆monoclinic5.5–6.51.664–1.733.22–3.38intense green
FluoriteFluoriteCaF₂cubic41.432–1.4343.18purple, green, blue, yellow, colorless
PainitePainiteCaZrAl₉O₁₅(BO₃)hexagonal7.5–81.787–1.8164.01red, brownish red, orange-red
TaaffeiteTaaffeiteBeMg₃Al₈O₁₆hexagonal8–8.51.716–1.7283.61–3.67mauve to purple, purplish red, grayish violet, colorless
GrandidieriteGrandidieriteMgAl₃BSiO₉orthorhombic7–7.51.583–1.6222.94–2.98greenish blue to blue-green
BenitoiteBenitoiteBaTiSi₃O₉hexagonal6–6.51.757–1.8053.65–3.68violetish blue, colorless, rarely pink
JeremejeviteJeremejeviteAl₆B₅O₁₅(F,OH)₃hexagonal6.5–7.51.637–1.6533.28–3.31colorless, pale blue, blue, yellow
PoudretteitePoudretteiteKNa₂B₃Si₁₂O₃₀hexagonal51.511–1.5322.51–2.53colorless to pale pink, purple-pink
SerendibiteSerendibiteCa₂(Mg,Al)₆(Si,Al,B)₆O₂₀triclinic6.5–71.701–1.7063.42–3.52grayish blue, blue-green, black
PearlNacre (calcium carbonate)CaCO₃organic2.5–31.52–1.692.6–2.85white, black, gray, yellow, orange, pink, lavender, green, blue
AmberFossil resinC₁₀H₁₆Oorganic2–2.51.541.08yellow, orange, brown; rarely blue or green
Precious coralCoralliidae skeletonCaCO₃ (calcite)organic3.5–41.486–1.6582.6–2.7white, pink, salmon, red
JetLigniteC with impuritiesorganic2.5–41.661.19–1.35black to dark brown
(Fig. 03)Species treeSpecies → variety

One mineral,
many names.

Ruby and sapphire are both corundum. Emerald and aquamarine are both beryl. The trade names follow color; the species follows chemistry and structure.

Fig. 01.2

Species and their varieties

10 species → 36 trade varieties

  1. DiamondC
    • Yellow (canary)yellowNitrogen (isolated N gives canary yellow)
    • Blueblue to grayish blueBoron (type IIb)
    • Pinkpink to redLattice defects from plastic deformation
    • GreengreenVacancies (GR1) from natural radiation
  2. CorundumAl₂O₃
    • Rubyorangy red to purplish redCr³⁺
    • Blue sapphireblueFe²⁺–Ti⁴⁺ intervalence charge transfer
    • Pink sapphirepinkCr³⁺
    • Yellow sapphireyellowFe³⁺ and trapped-hole (h•–Fe³⁺) centres
    • Color-change sapphirechanges between daylight and lamplightV³⁺
  3. BerylBe₃Al₂Si₆O₁₈
    • Emeraldgreen to bluish greenCr³⁺ and/or V³⁺
    • Aquamarinepale blue to greenish blueFe²⁺
    • Morganitepink to peachMn²⁺
    • Heliodorgreenish yellowFe³⁺
    • Red berylredMn³⁺
    • GoshenitecolorlessNo significant chromophore
  4. ChrysoberylBeAl₂O₄
    • Alexandritegreen in daylight, red in incandescent lightCr³⁺
    • Cat’s-eye (cymophane)yellowish with a bright chatoyant bandParallel needles or tubes (chatoyancy)
  5. QuartzSiO₂
    • Amethystviolet to purpleFe³⁺ plus natural irradiation
    • Citrineyellow to orangeFerric iron; most is heated amethyst
    • Smoky quartzbrown to gray-blackAl color centers from natural radiation
    • Rose quartzpale pinkDumortierite-related mineral fibers
    • Chrysopraseapple greenNickel compounds
  6. Elbaite (tourmaline)Na(Li₁.₅Al₁.₅)Al₆Si₆O₁₈(BO₃)₃(OH)₄
    • Rubellitepink to redManganese
    • IndicoliteblueIron
    • Paraíbaneon blue to greenCu²⁺ (with Mn)
  7. SpinelMgAl₂O₄
    • Red spinelred to pinkCr³⁺
    • Blue spinelblue to violetFe²⁺
    • Cobalt spinelsaturated blueCo²⁺
  8. SpodumeneLiAlSi₂O₆
    • Kunzitepink to violetManganese
    • HiddenitegreenCr³⁺
  9. Nacre (aragonite)CaCO₃
    • Akoya pearlwhite to cream, rose overtoneAragonite platelets in conchiolin; overtone from interference
    • South Sea pearlwhite to silver, or goldenNacre of the mollusc; golden tone follows the shell lip
    • Tahitian pearlgrey to near black, green overtoneNacre of the black-lipped mollusc
    • Freshwater pearlwhite, peach, lavenderFreshwater mussel nacre; tone follows the shell
  10. Olivine(Mg,Fe)₂SiO₄
    • Peridotyellowish green to greenIron (Fe²⁺) in the olivine structure, not a trace element
    • Meteoritic peridotyellowish greenThe same iron; these crystals came to earth in meteorites
(Fig. 04)HardnessMohs 1 to 10

Ten steps,
not ten equal steps.

Mohs ranks minerals by which scratches which. Measured on a hardness tester, diamond is several times harder than corundum, the next step down. Select a bar to compare.

Fig. 03.2

Mohs scale against measured hardness

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10

Selected

Diamond

Mohs
10
Vickers (GPa)
115
vs. step below
5.9×

Vickers microhardness in GPa (Broz, Cook & Whitney 2006) Equal steps (if Mohs were linear)

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