We are offering garnet.Chemical composition complex silicates with widely varying chemical composition but similar structures. color usually dark brownish or purplish red garnet and almost any color expect blue. refractive index 1.74-1.94. Isometric. durability hardness 6.5-7.5. crystal structure isometric (cubic). specific gravity 3.4-4.2 sources occurrence czechoslovakia, india, north carolina, tanzania