7.50 Ct. Boulder Opal from Australia

This listing from The Natural Gemstone Company describes a single, natural Boulder Opal of 7.50 carats, presented in a freeform outline with precise dimensions of 13.50 x 11.09 x 5.05 mm, executed as a tablet cut with a flat, low profile and an excellent polish. The opal displays intense color intensity, with dominant blue and green play of color and selective areas showing warm orange flashes, distributed in a mosaic to broad flash pattern across the polished surface. As a true Boulder Opal from Australia, the gem retains portions of its ironstone host visible on the pavilion, providing a stable natural backing that enhances contrast and saturation of the play of color. No enhancement has been made to this piece, the material is untreated, and the polish and surface finish confirm excellent lapidary control over the tablet profile, preserving thin color seams and surface stability.

Technically, the tablet cut emphasizes preservation of color bar thickness and seam orientation, maintaining strong diffraction from the internal silica sphere layering while minimizing bulk removal, a strategy often used with boulder material to retain the natural ironstone matrix as a backing. The freeform geometry offers maximum yield from the rough, producing a unique pattern orientation that is well suited to bezel and inlay settings where the ironstone edge can be structurally supported. Surface condition is excellent, with a high polish that optimizes light return and color play across viewing angles. For practical considerations, opal hardness and stability typically range near 5.5 to 6.5 on the Mohs scale, and boulder opal with ironstone backing provides improved durability over potch only material, though care with ultrasonic cleaning and extreme temperature changes is advised. This untreated Australian Boulder Opal represents a balance of vivid, intense play of color, thoughtful tablet cutting to preserve color seams, and durable natural backing, making it an ideal component for collectors and designers seeking a technically refined, one of a kind opal.