Gemstone refers to all the beautiful gems and precious stones, they have beautiful color. high hardness invariable under chemicals in the atmosphere and the precious ore. They have bright colors, crystal texture shine bright, haro and durable, while rare occurrence, bright colorful gems, through color, gloss, transparency, refractive index and shape of cut brings their unique and beautiful. Because of its internal crystallization often contain inclusions, double-crystal grain, crystal structure, causing optical interference diffraction and scattering phenomena in the light there will be some special optical effects. common special optical effects starlight effect, cat's eve effect, color effect,moonlight effect, swim-color effect, Venus effects, light effects.