AI Appraisal Estimate

This is a significant natural Australian Black Opal, weighing 1.1 grams and measuring 1.6 inches by 1 inch. The stone is cut into a classic oval cabochon shape with a smooth, high-polished dome that enhances its inner light. It exhibits a striking 'play-of-color' dominated by vibrant electric greens and deep cobalt blues set against a dark body tone. The fire pattern is fragmented and dynamic, showing a 'flagstone' style where distinct patches of color shift as the light changes. Purchased in 1968, the specimen is nearly 60 years old and remains in excellent condition with no visible cracks or surface abrasions, indicating high-quality hardness and careful preservation. The internal geometry of the color flashes suggests a genuine sedimentary origin, consistent with premium Lightning Ridge material. The craftsmanship of the cut is symmetrical and professional, maximizing the surface area and brilliance of the gemstone's natural inclusions.

Based on the provided images and documentation, I have examined this striking Australian Black Opal. Weighing 1.1 grams (approximately 5.5 carats), the stone features a classic oval cabochon cut that effectively displays its vibrant play-of-color. The gem exhibits a desirable dark body tone with intense electric green and cobalt blue flashes in a dynamic flagstone pattern, strongly characteristic of material sourced from Lightning Ridge. The gemstone appears to be in excellent condition with no visible crazing, fractures, or significant surface abrasions, which is remarkable given its 1968 provenance. The symmetrical cut maximizes the surface area and brilliance. In the current market, authentic Lightning Ridge black opals of this era and quality are highly sought after by collectors and jewelers due to the depletion of historic mining areas. Demand remains very strong for stable, un-crazed vintage opals with vibrant blue-green fire. However, please note that an appraisal from photographs has inherent limitations. The stated dimensions (1.6 by 1 inches) are unusually large for a 5.5-carat weight, suggesting it may be a doublet or an exceptionally thin slice, which dramatically impacts value. To definitively confirm its solid nature, origin, and exact carat weight, an in-person gemological examination and potentially refractive index testing are required. Pending physical verification that this is a solid, natural, untreated black opal, I place its estimated retail replacement value in the aforementioned range.