Ethiopian opal, 3.707 carats

Technical details: Type: Ethiopian Opal (Opal) Weight: 3.707 carats Shape: Cabochon (Cabochon) Color: White Clarity: Uncategorized (Uncategorized) Transparency: Opaque (Opaque) Hardness: 5.5-6.5 Treatment: Untreated Origin: Ethiopian Certification: Electronic certificate (PDF) from the Saudi Laboratory (MT) - website (www.mtgl.com.sa) The opal (Opal) is a semi-precious (non-crystalline) mineral of Hydrated Silica, and is known for its great diversity in appearance. The most famous type is the precious opal (Precious Opal), which features a unique visual phenomenon called play-of-color, where iridescent flashes of different spectral colors change with the viewing angle, due to light interference with arranged microscopic silica spheres. The common opal (Common Opal), does not show this phenomenon but comes in a variety of colors. Opal forms in cavities of sedimentary and volcanic rocks when silica-rich water solutions are deposited.