Site Contents

Alphabetical Gemstone List
Click on a letter for a list of gems:

A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P| Q| R| S| T|U| V| W| X|Y |Z

Gemstones that begin with the letter "C"

Gemstone Crystal System Density Hardness Refractive index Treatments

coral
Calcareous Concretions

aggregate 2.85 2.5-4.0 1.530-1.685 none known

calcite
Calcite

trigonal 2.70 3.0 1.486-1.658 dying, filling, irradiation

cassiterite
Cassiterite

tetragonal 6.95 6.0-7.0 1.997-2.093 none known

carnelian
Carnelian

microcrystalline 2.65 7.0 1.535-1.539 dying, filling

chalcedony
Chalcedony

microcrystalline 2.65 7.0 1.535-1.539 dying

charoite
Charoite

aggregate 2.68 5.0-6.0 1.550-1.559 none known

chlorastrolite
Chlorastrolite

aggreegate 3.20 5.0-6.0 1.650-1.660 none known

chrysoberyl
Chrysoberyl

orthorhombic 3.72 8.5 1.746-1.755 none

chrysocolla
Chrysocolla

microcrystalline 2.00-2.24 2-4 1.54 none

chrysoprase
Chrysoprase

microcrystalline 2.65 7 1.564-1.660 dying

citrine
Citrine

hexagonal 2.66 7.0 1.544-1.553 heat

copal
Copal

organic 1.08 2.0 1.540 heat, heating in oil, dying

coral
Coral

organic 2.65 3.5-4.0 1.486-1.658 dying

corundum
Corundum

trigonal 4.00 9.0 1.762-1.770 heat, fracture filling

cuprite
Cuprite

cubic 6.14 3.5-4.0 .2.849 none known