Probably English, 17th century.
Ring size Q UK / 8 US.
The bezel is engraved with the letters ‘IHS’ (the letters above the head of Christ during his crucifixion, the letters are an abbreviation of the Latin ‘Iesus Hominum Salvatore’ which translates in English as ‘Jesus, Saviour of Men’), along with the Arma Christi (instruments of the passion, relating to the crucifixion of Christ).
The small silver bumps on the hoop of this ring indicate its use as a ‘decade’ ring, a piece of jewellery designed to help its owner count prayers, similar to a larger rosary. Each nodule represented a ‘Hail Mary’ or ‘Our Father’ prayer from the rosary. Although rosaries were banned in England starting in 1538, with the ban reinforced by the 1547 Injunctions and a 1571 statute that prohibited overt Catholic symbols like the Agnus Dei, crosses, images, and rosary beads, decade rings were not specifically forbidden. As a result, these rings continued to be made and worn by ‘recusant’ Catholics who resisted adopting Protestant practices.
Two examples can be found in the collection of the Victoria and Albert Museum, London, Accession numbers: M.816-1926 and M.817-1926.
A similar example, catalogued as English can be found in ‘Rings: Alice and Louis Koch Collection’, item no. 803, page 247.