21.77 Ct.Tw.Total Carat Weight Cabochon Opal Pair from Australia

This paired set of Australian Boulder Opal cabochons is presented by The Natural Gemstone Company, and is specified to exacting standards for the experienced buyer. The two pieces weigh 9.69 carats and 12.08 carats respectively, and are cut into round outlines to a high degree of uniformity. The first specimen measures 15.70 x 15.50 x 4.30 mm, the companion measures 15.70 x 16.10 x 5.10 mm. Both stones are single cabochons with a convex dome profile, exhibiting an intense color intensity and an excellent polish. These materials are furnished as doublets, with the natural opal layers stabilized on a dark backing to enhance the visual depth of the play of color. The documented origin is Australia, and the opal type is Boulder Opal, originating from ironstone host rock that contributes to the characteristic matrix and tonal background. All measurements and weights have been determined with calibrated instruments in our facilities, to provide reliable specifications for design and evaluation.

From a gemological and lapidary perspective these Boulder Opals demonstrate classic features that distinguish them from other opal types. The matrix interplay between the brown ironstone and the opalized seams yields a mosaic of multi color patches, with a predominance of vivid greens and blues set against warm orange and brown areas. The play of color is pronounced, described here as intense, indicating strong diffraction effects within the hydrated silica layers. The patterning is broad and patchy rather than pinfire, creating expansive flashes that read well across a jewelry face. Because these are doublets, the thin opal veneer is presented against a backing that increases apparent color saturation and contrast, which is particularly effective for Boulder Opal material where the natural ironstone contributes complementary hues. Careful observation under varied angles reveals shifting color dominance and lively iridescence, attributes that are most desirable for collectors and designers seeking dynamic visual impact.

The cabochon cutting and finishing have been executed with attention to symmetry, dome height, and edge integrity, optimizing both aesthetic performance and structural resilience. The domes are proportioned to balance face up color presentation with sufficient opal thickness, an important consideration given the doublet construction. The slightly differing thicknesses, 4.30 mm and 5.10 mm, allow for complementary mounting strategies while maintaining a matched appearance in diameter and color distribution. Polishing reaches a high gloss with minimal surface abrasions, indicating the use of fine diamond abrasives and felt or leather laps in final stages to achieve a smooth optical surface. The cutters have maintained continuous grain flow from edge to crown, avoiding abrupt flats or bevels that could interrupt the play of color. The backings are neatly applied and sealed, producing stable composite pieces suitable for bezel and inlay settings, while preserving the characteristic ironstone inclusions that define Boulder Opal aesthetics.

For practical use and long term appreciation these paired Boulder Opal doublets perform well in a range of jewelry applications. The round shapes and near identical diameters make them ideal for matched stud earrings, paired pendant elements, or matched bezel set accents in a custom design. Given the doublet enhancement, recommended setting choices include protective bezels and settings that reduce exposure to solvents and prolonged heat, as adhesives and the thin opal layer may be sensitive to extreme conditions. Cleaning should be performed with mild soap and lukewarm water, using a soft cloth, and avoiding ultrasonic or steam cleaners. For valuation considerations, provenance from Australia and the Boulder classification add premium attributes, as does the intense color intensity and excellent polish. At The Natural Gemstone Company we document enhancement as doublet, and we supply certified measurements and imagery to support design and appraisal needs. These two opals present a technically refined and visually vibrant option for connoisseurs and designers who appreciate the intricate interplay of natural matrix and engineered backing in high quality Boulder Opal doublets.