6.76 Ct. Multi Color Boulder Opal (Ironstone Opal) from Australia

This 6.76 carat oval tablet cut boulder opal, Ironstone Opal, presents a deliberately thin, broad profile that emphasizes surface play of color, the tablet cutting style yielding a flat plan view with minimal dome to maximize spectral dispersion. The piece measures 22.00 by 8.50 by 3.98 mm, and the cutter has oriented the opal slice to preserve continuous color seams across the long axis, a technique that reduces unwanted banding and maintains strong color flow. Transparency is classified as translucent, and the clarity grade is eye clean evaluated at eye level, indicating an absence of occluding inclusions or fractures visible without magnification. Color intensity is recorded as intense, the polish is excellent, and there has been no enhancement, which together confirm that the optical effects are native to the Australian host material. The identification is Boulder Opal, Ironstone Opal, and the ironstone backing is thin yet stable, retained where beneficial to support the tablet profile while avoiding any darkening of the play of color.

From a lapidary perspective the tablet cut on this specimen demonstrates precise material management, with careful trimming of ironstone matrix at the pavilion edge to balance durability against maximum face up color. The cutting removed excess thickness to achieve a 3.98 mm profile, a dimension that optimizes light transmission through the opal layer while maintaining structural integrity on the ironstone substrate. Surface polishing reaches an excellent grade, producing clean facetless surfaces that allow microstructure interference colors to read as saturated flashes rather than washed patches. The pattern displays multi color loci with strong red and green shifts under directional light, and the dispersion characteristics indicate tightly packed silica sphere layering, responsible for the intense spectral separation. For jewelry applications this tablet cut is suitable for low bezel or flush settings that protect the thin edge, and the flat profile is ideal for inlay work or elongated, contemporary designs. The Natural Gemstone Company offers this Australian boulder opal as a museum quality slice for designers and collectors who require technical exactness, natural provenance, and uncompromised optical performance.