Ethiopian opal, 2.434 carats

Technical details: Type: Ethiopian Opal (Opal) weight: 2.434 carats shape: Pear color: Black and multicolored clarity: Uncategorized transparency: Opaque hardness: 5.5-6.5 treatment: Smoke Treated origin: Ethiopian certification: Electronic certificate (PDF) from Saudi Laboratory (MT) - website (www.mtgl.com.sa) 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 Precious Opal, which features a unique optical 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. 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.