: Formed within ironstone, often showing dramatic, unique patterns.
: Thin slices of opal glued to a dark backing (and sometimes capped with quartz). These offer the look of expensive black opal at a fraction of the cost—often around 1/30th the price of a solid black opal. Check Play-of-Color & Pattern :
: Only buy from sellers who accept returns, as the stone’s appearance can vary significantly between digital screens and real-life lighting. Estimated Pricing & Trusted Sources How Much Are Opal Earrings Worth? - Angara
: 100% natural stone. These are the most durable and valuable.
: Ensure the jeweler provides a Certificate of Authenticity stating the opal’s origin and any treatments (like smoking or sugar-acid treatments).