Large rock crystal ring, circa 1880. Rock crystal is one of the most historically important materials in jewellery design, appearing in medieval and renaissance jewels across Europe. Prized for its perfect purity and transparency, the ancient Greeks named the stone Krustallos, believing it to be a form of supercooled ice. For followers of crystal healing, rock crystal is also particularly important, believing that the stone possesses energising qualities, and bringing the wearer in touch with the spiritual world. This rock crystal, with its antique cushion cut and a slightly hazy feel to its play of light, is a beautiful choice as the central stone to this ring, its simple design in buttery yellow gold bringing out the warmth in this subtle and charming stone.