Vintage Oval Black Onyx or Glass Cabochon Ring

This item is a vintage-style ring featuring a prominent oval cabochon-cut stone, appearing deep black in color, likely black onyx or a high-quality glass paste. The stone is set into a silver-toned metal mounting, possibly sterling silver or a plated alloy, which exhibits a darkened patina consistent with age. The bezel surrounding the central stone is detailed with a decorative textured or beaded border, often referred to as milgrain or rope-twist detailing, which suggests a mid-20th-century design influenced by Art Deco or Victorian revival styles. The size of the face is approximately 1.5 cm by 1.2 cm, fitting comfortably within the palm of a hand. The metal shows minor surface scratches and significant oxidation in the recessed areas of the metalwork, which highlights the design but also indicates regular wear. No clear maker's marks or hallmarks are visible in the provided image, though such stamps would typically be found on the interior of the band. The craftsmanship appears to be of standard commercial quality for costume or semi-precious jewelry from the 1940s to 1970s. The overall condition is fair to good, with the stone retaining a high gloss and the mounting remaining structurally intact despite the surface tarnish.

Based on my visual examination of the featured oval black cabochon ring, I estimate its fair market value between $45 and $75. The piece exhibits characteristics typical of mid-century Victorian revival or Art Deco-inspired costume jewelry, likely dating from the 1950s to the 1970s. The 'milgrain' bezel and silver-toned patina suggest a mass-market production intended for the semi-precious or costume jewelry market. The dark stone, while visually consistent with black onyx, could also be 'French Jet' (black glass) or a thermoset plastic, both common for this era. Condition is fair to good; the significant oxidation in the recesses provides an attractive contrast, though the surface scratches indicate consistent wear. Markets for this type of vintage jewelry remain stable but saturated. Comparable sales on secondary platforms for unmarked, silver-toned onyx rings typically fall under $100 unless a prestigious maker's mark (such as Georg Jensen or a noted Mexican silver smith) is found. Limitations: This appraisal is based solely on digital images. A physical inspection is required to determine the metal’s purity via acid testing or XRF analysis to confirm if it is .925 sterling silver or a base metal alloy. Furthermore, a gemological loupe examination is necessary to check for natural mineral inclusions or mold lines/bubbles, which would differentiate genuine onyx from glass. Provenance or a hallmark would significantly increase the upper-end valuation.