Opal gem color is most a kind of gorgeous, it set red, orange, yellow, green, cyan, blue, purple seven color for a body, attracts people’s attention to their own colorful, magnificent and varied colors Jewelry. Many brands have made opal jewelry. Opal hardness is 5 ~ 6.5, refractive index is 1.44 ~ 1.46, density is 2 ~ 2.1, transparent, translucent, opaque body. Opal is a hydrous amorphous silica body, is a suitable gemstone jewelry making. Opal rotation, with raising the irradiation direction of the light source will appear the phenomenon of dramatic color change, so many companies used to embedded in the jewelry. This color change is due to natural light through the stones inside the crystal, by the micro cracks and structure the space light caused by the interference of, so this gem is by the women like them in the selection of gemstone, opal is among them a kind of choice. The internal structure of the silica opal is arranged by numerous chondrite composition rules. There are water and air to fill the gap between the spherulites and spherulite, when light passes through, water and air voids of light diffraction and factoring out the variety of different wavelengths of light. Then there is the colorful color variation. There are a variety of opal color, mainly according to the color of the color of the base color and changing color opal to opal classification and nomenclature. According to the opal base color, can be divided into black opal, White Opal opal, 3 varieties. Black opal is a relatively rare, rare Jiapin opal. Black opal generally opaque, the color is black and dark gray, dark blue, also has a basement dark green, dark brown. Stone is changed color Venus like, reflecting a magnificent scene is Jiapin, this is obviously that jewelry company(Bvlgari jewelry,Cartier jewelry,Hermes jewelry etc..) of a favorite species. White opal is a milky white, light grey, grey base, floating beautiful change color opal. Compared with black opal, different color only. The surface is white opal, multistar wire sheet Venus, is one of the most common. Water is usually translucent, sometimes there will be a rainbow color. There are opaque and transparent. Transparent white opal is blue, green, and unique color alternating purple or yellow or blue and yellow. Fire for more than the color orange red, orange, yellow, brown. Because most of the fire opal color red like fire, pure and bright, hence the name “fire opal”. It is transparent or translucent, sometimes have changed color, the color change is not obvious sometimes mow. In addition, according to the change of color and color opal color appearance.