Vintage Round Brilliant Diamond Solitaire Ring in Two-Tone Illusion Setting

This is a fine jewelry ring featuring a center round brilliant-cut diamond, estimated to be approximately 0.25 to 0.40 carats based on visual scale. The gemstone is mounted in a vintage-style square 'illusion' head made of white metal (likely white gold or platinum), which is designed with reflective, faceted metal corners to make the central diamond appear larger and more prominent. This white metal head is soldered onto a tapered yellow gold shank, indicating a two-tone construction characteristic of pieces from the mid-20th century, specifically the Retro or early Mid-Century Modern periods (circa 1940s-1950s). The shank shows a polished finish with slight thinning consistent with long-term wear, and the prongs appear intact but may require professional inspection for metal fatigue. The design features a decorative gallery under the head with subtle openwork. There are no visible maker's marks or purity stamps in the photograph, though they would typically be found on the interior of the band. The craftsmanship reflects a mass-produced but high-quality commercial standard common for engagement rings of that era, emphasizing durability and optical enhancement of the stone.