15.48ct Opal and Diamond Platinum Cocktail Ring

This is a significant cocktail ring featuring a large, oval-shaped cabochon opal with a reported weight of 15.48 carats. The opal serves as the central focal point, displaying a vibrant milky-white body color with a strong 'play-of-color' that includes flashes of neon green, yellow, and orange. The stone is secured by a six-prong setting in a high-polish white metal, identified by the listing as platinum. The shank is accented on the shoulders with small, round brilliant-cut diamonds grain-set into a leaf-shaped or scrolled decorative motif. One of the secondary images shows a '900' or 'PT900' hallmark on the interior of the band, confirming the platinum purity. The ring's construction is robust, designed to support the substantial size of the gemstone. Based on the scale shown next to a ruler and on a mannequin hand, the opal is approximately 20-25mm in length. The condition appears to be excellent with no visible crazing or cracks to the opal's surface, though the white metal shows typical light surface micro-scratches consistent with gentle wear. The style is a classic late 20th-century or contemporary estate design, emphasizing the natural beauty of the oversized gemstone through a minimalist but elegant mount.

I have conducted a visual examination of the 15.48ct Opal and Diamond Platinum Cocktail Ring. This piece is headlined by a significant oval cabochon precious opal. The stone exhibits a desirable milky-to-translucent base with a broad-flash play-of-color, predominantly displaying neon greens and oranges. The PT900 signature indicates a Japanese or high-tier Asian manufacturing origin, known for utilizing high-purity platinum. The setting is professionally executed with scrolled shoulders featuring grain-set round brilliant diamonds, which appear to be of G-H color and VS-SI clarity based on their luster. The condition is excellent, notably lacking 'crazing' (surface cracking) which often plagues opals of this size. High-quality opals exceeding 15 carats are rare, particularly when free of host-rock inclusions. Current auction and estate markets show a steady demand for 'statement' cocktail rings, though the opal market is sensitive to origin (e.g., Australian vs. Ethiopian). In-person inspection is required to confirm if the opal is a solid stone, a doublet, or a triplet, as this drastically alters the value. Furthermore, a gemological report is necessary to determine the stone's origin and to confirm the absence of stability treatments like resin impregnation. Without a laboratory certificate, this valuation assumes a natural, solid opal of likely Australian origin. This estimate reflects the fair market value for an estate piece of this caliber in a retail or high-end secondary market setting.