Synthetic Gemstone Refractive Index List

Synthetic and man-made gem materials sorted by refractive index, lowest to highest. No natural stones are listed. Materials we carry are highlighted and link to the shop.

This list is RI only, for picking a design. For hardness, specific gravity, dispersion, crystal system and critical angle on the materials we carry, see the full property table in the field guide.

Refractive index Material Birefringence Growth method Our shop
1.378–1.390 Magnesium fluorideMgF₂ 0.012 Bridgman Not stocked
1.392 Lithium fluorideLiF None Bridgman Not stocked
1.434 Lab-grown fluoriteCaF₂ None Bridgman Not stocked
~1.45 Lab-created opal, no resinSiO₂·nH₂O None Sedimentation Not stocked
1.45–1.47 Impregnated opal, 15% resinSiO₂ + polymer None Sedimentation, resin Shop
1.474 Barium fluorideBaF₂ None Bridgman Not stocked
~1.49 Aurora opal, 80% resinSiO₂ + polymer None Silica in resin Shop
~1.52 X-CubeOptical glass None Optical glass Shop
1.544–1.553 Hydrothermal quartzSiO₂ 0.009 Hydrothermal Shop
1.561–1.564 Flux-grown emeraldBe₃Al₂Si₆O₁₈ 0.003 Flux Not stocked
1.568–1.579 Hydrothermal emerald and berylBe₃Al₂Si₆O₁₈ 0.005–0.009 Hydrothermal Shop
1.634–1.670 Synthetic forsteriteMg₂SiO₄ 0.036 Czochralski Not stocked
1.65–1.70 NanositalGlass-ceramic Varies Controlled crystallization Shop
1.654–1.670 Synthetic phenakiteBe₂SiO₄ 0.016 Flux Not stocked
1.718 Polycrystalline (HIP) and flux spinelMgAl₂O₄ None HIP, flux Shop
~1.728 Flame fusion spinelMgAl₂O₄ None Flame fusion Shop
1.737 Synthetic periclaseMgO None Arc fusion Not stocked
1.746–1.755 Synthetic alexandriteBeAl₂O₄ 0.009 Czochralski Shop
1.762–1.770 Synthetic corundum (sapphire, ruby)Al₂O₃ 0.008 Flame fusion, Czochralski, TGT Shop
~1.78–1.89 KTPKTiOPO₄ ~0.11 Flux, hydrothermal Not stocked
~1.82 LYSO(Lu,Y)₂SiO₅ Slight Czochralski Shop
1.833 YAGY₃Al₅O₁₂ None Czochralski Shop
~1.84 LUAGLu₃Al₅O₁₂ None Czochralski Shop
~1.90 GAGGGd₃(Al,Ga)₅O₁₂ None Czochralski Shop
1.918–1.934 Synthetic scheeliteCaWO₄ 0.016 Czochralski Not stocked
~1.92–1.95 YAPYAlO₃ ~0.03 Czochralski Shop
~1.95 TGGTb₃Ga₅O₁₂ None Czochralski Not stocked
1.97 GGGGd₃Ga₅O₁₂ None Czochralski Shop
1.993–2.215 Yttrium orthovanadateYVO₄ 0.222 Czochralski Not stocked
2.013–2.029 Synthetic zinciteZnO 0.016 Hydrothermal Not stocked
~2.10 Bismuth germanate (BGO)Bi₄Ge₃O₁₂ None Czochralski Not stocked
2.15–2.18 Cubic zirconiaZrO₂ None Skull melting Shop
~2.18 Lithium tantalateLiTaO₃ ~0.004 Czochralski Not stocked
2.21–2.30 Lithium niobateLiNbO₃ 0.09 Czochralski Shop
2.37 Lab-grown sphaleriteZnS None CVD Not stocked
2.409 Strontium titanateSrTiO₃ None Flame fusion Shop
2.417 Lab-grown diamondC None HPHT, CVD Not stocked
~2.57 Bismuth germanium oxideBi₁₂GeO₂₀ None Czochralski Not stocked
2.616–2.903 Synthetic rutileTiO₂ 0.287 Flame fusion Shop
2.648–2.691 Synthetic moissaniteSiC 0.043 Sublimation Shop

Reading the numbers

A single value means the material is singly refractive. A range shows the low and high readings of a doubly refractive material or the published spread for that material. A ~ marks an approximate value that can shift with dopants and batch. Values are near 589 nm, except YVO₄ at 633 nm and KTP at 532 nm.

Why it matters at the bench

Higher RI means a smaller critical angle: about 40.5° at RI 1.54, 34.4° at 1.77, and 24.4° at 2.42. Pavilion angles must stay above the critical angle or light leaks out the back, so low-RI materials need steeper pavilions. Pick a design written for the RI you are cutting.

Field guide: Grown, not found  ·  Full property table  ·  All materials