emerald 8 octahedrons spinel 7.5 hexagonal prisms beryl 7 three-sided prisms tourmaline 7 dodecahedrons or trapezohedrons garnet 7 non-crystalline prase or plasma 6.5-7 non-crystalline, olive color olivine 6.5 yellow green color, rather opaque epidote 6 non-crystalline, pearly luster opal 5.5 short eight-sided prisms pyroxene 5.5 long six-sided prisms amphibole 5 hexagonal prisms apatite 4 cubes fluorite 3.5 effervesces in acid cerrusite 2.5-4 somewhat greasy feel, massive or serpentine fibrous 2 in mica-like scales, non-elastic chlorite 1 greasy feel, fibrous or scaly talc Red 9 hexagonal prisms ruby 8 octahedrons spinel 7 three-sided prisms tourmaline 7 dodecahedrons or trapezohedrons garnet 7 hexagonal rose quartz 7 non-crystalline jasper or carnelian 6 pearly luster fire opal 4 cubes, rose tints fluorite 2-3 pink mica-like scales lepidolite Blue 9 hexagonal prisms sapphire 7 & 4.5 blade-like crystals cyanite 6 non-crystalline masses turquois 5.5-6 in igneous rocks sodalite 4 azure color azurite 3.5 effervesces in acid, heavy cerrusite 2-4 earthy masses, turquoise color chrysocolla Violet 7 hexagonal prisms amethyst 4 cubes fluorite Yellow 9 hexagonal prisms oriental topaz 8 octahedrons spinel 8 hexagonal prisms topaz 4 cubes fluorite Brown 9 hexagonal prisms corundum