A belief in the magical or curative properties of gemstones, minerals and other natural materials has long existed. Toadstones were especially popular in the Middle Ages and Renaissance periods. They were most often set in rings - the natural shape of the toadstone fitted a ring bezel well, and the toadstone could be worn daily and touched or monitored for any changes. They were highly valued and included in the stock of many jewellers. An unmounted toadstone was found as part of the Cheapside Hoard (now in the Museum of London), the stock of a 17th century jeweller which was found in the cellar of a London house in the early 20th century.

A 'toadstone' is actually the fossilised tooth of a fish called 'Lepidotes'. Also known as 'crapaudine' or 'crappot' it is a brown or orangeish substance believed to come from a toad's head. It was highly valued and reputed to protect the wearer against kidney diseases, to cure the bite of venomous creatures and to detect poison. It was also thought to protect pregnant women from fairies and demons and to prevent their child being exchanged for a changeling. When set in a ring it would give off heat in the presence of a poison. This was described by Fenton in 1569 "Being used in rings they give forewarning of venom".

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.

Edmund Waterton used the fortune which was made by his family’s involvement in the British Guiana sugar plantations to put his collection together. His grandfather owned a plantation known as Walton Hall and his father, Charles Waterton, went to Guiana as a young man to help run La Jalousie and Fellowship, plantations which belonged to his uncles. When slavery was abolished in the British territories, Charles Waterton claimed £16283 6s 7d in government compensation and was recorded as having 300 slaves on the Walton Hall estate.