Ring with rose opal

Opal is a fascinating gemstone known for its unique play of colors and variety of shades. By its nature, it is an amorphous hydrated silica (SiO₂·nH₂O) containing a variable amount of water (usually 3-10%, sometimes up to 20%). 

The most striking property of opal is its ability to exhibit a "play of colors" or opalescence - a bright rainbow glow that changes depending on the angle of view. This phenomenon is caused by the diffraction of light by the ordered microscopic spheres of silica within the stone. The color of the opal body (the main background) can vary from transparent, white, gray and yellow to orange, red, green, blue, purple and even deep black.

Main types of opal:

• Precious Opal: Highly prized for its bright and intense play of color on a variety of backgrounds (from white to black).
• Fire Opal: Characterized by a rich, translucent or transparent body of yellow, orange or red. May exhibit play of color, but is prized primarily for its primary color.
• Common Opal / Potch: Does not exhibit play of color, but may be attractive due to its color, patterns, or transparency (e.g., milky, wood, hyalite).
• Boulder Opal: Thin layers or veins of precious opal naturally intergrown with the parent rock (usually ironstone).
• Matrix Opal: Precious opal that fills pores or cracks in the parent rock, creating a "matrix" pattern.

Natural opal is a popular choice for jewelry - rings, pendants, earrings, as well as a valuable object for mineral collectors. Due to its beauty and uniqueness, opal has been considered a stone of inspiration and good luck since ancient times.