African opal, 6.484 carats

Technical details: Type: African Opal (Opal) weight: 6.484 carats shape: Cabochon (Cabochon) color: Black clarity: Uncategorized (Uncategorized) transparency: Opaque (Opaque) hardness: 5.5-6.5 treatment: Dusted (Smoke Treated) origin: African certification: Electronic certificate (PDF) from the Saudi (MT) laboratory - website (www.mtgl.com.sa) The opal (Opal) is a semi-precious (non-crystalline) mineral of hydrated silica (Hydrated Silica), known for its great diversity in appearance. The most famous type is the precious opal (Precious Opal), which features a unique optical phenomenon called play-of-color, where iridescent flashes of different spectral colors change with the viewing angle, resulting from light interference with microscopic silica spheres arranged. As for common opal (Common Opal), it 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.