There are many products called opal, but why they would not look the same?

Opal is an amorphous form of silica related to quartz, a mineraloid form, not a mineral. However, there is opal with or without color effect. Only opal with color dynamicity could be classified as precious gemstone and they are called “Precious Opal”. High-quality precious opal would have bright rainbow-like colors and while rotating; there will be various of magical brilliance and gorgeous color, with attractive color changes.

Among the opal categories, most of them are general opal, only a very small percentage of them are precious opal. Opal has various colors, such as black, grey, white, brown, pink, orange, yellow, green, blue & transparent, etc . In the jewelry industry, as general opal is in milky white and without any color change effects, its commercial value is not high and could not be classified as precious gemstone.