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.

This ring forms part of a collection of over 600 rings and engraved gems from the collection of Edmund Waterton (1830-81). Waterton was one of the foremost ring collectors of the nineteenth century and was the author of several articles on rings, a book on English devotion to the Virgin Mary and an unfinished catalogue of his collection (the manuscript is now the National Art Library). Waterton was noted for his extravagance and financial troubles caused him to place his collection in pawn with the London jeweller Robert Phillips. When he was unable to repay the loan, Phillips offered to sell the collection to the Museum and it was acquired in 1871. A small group of rings which Waterton had held back were acquired in 1899.