During the Middle Ages, gemstones were most often set as polished but unfacetted cabochons. This ring is set with a sapphire which has been polished and set in a high, projecting bezel but remains a very irregular shape.
Sapphires were highly valued for their heavenly blue colour and supposed magical qualities. The lapidary of Marbodus, bishop of Rennes (1067-81) describes the properties of 60 gemstones. Sapphires were believed to cool the body, soothe headaches and ulcers, and cure stammers. Rings found in bishops' tombs suggest that they were particularly favoured as episcopal rings.