Quadruple Diamond, completed in 1967, presents De Wain Valentine's mastery of industrial materials as a vehicle for pure optical sensation. Measuring nearly eight feet square, the work commands an imposing physical presence while simultaneously dissolving its own materiality through the shimmering, light-reactive surface achieved with metallic flake lacquered polyester and fiberglass. The diamond form, repeated and stacked within the composition, generates a rhythmic geometry that shifts in character depending on the viewer's position and the ambient light conditions, producing an almost kinetic quality from an entirely static object. Valentine's deployment of automotive-grade finishes, a hallmark of California's Light and Space movement, elevates craft to conceptual purpose, making the surface itself the primary subject. Valentine developed this approach in close dialogue with the technological and cultural energy of Southern California in the 1960s, and Quadruple Diamond belongs to a pivotal early period when he was refining the formal vocabulary that would define his mature practice. The scale and symmetry of the work align it with minimalist concerns around presence and objecthood, yet the luminous, almost hallucinatory surface warmth places it firmly within the perceptual investigations associated with artists such as Larry Bell and Craig Kauffman. At a time when Valentine's large-scale cast resin discs have attracted considerable institutional and collector attention, this earlier fiberglass work offers a rare opportunity to study the foundational thinking behind his celebrated later output. The work is signed and carries strong provenance, presented in excellent structural condition consistent with its original fabrication quality. Collectors seeking historically significant examples of California Light and Space at an early and formative moment will find Quadruple Diamond to be a compelling and well-documented acquisition.