what was st catherine of siena's ring made out of

St. Catherine of Siena's ring was said to be made from a very unusual material—not gold or jewels, but from the holy foreskin of Jesus Christ. This ring was part of her "mystical marriage" to Christ, which she experienced around the age of 21. Some accounts claim the ring was invisible, symbolizing a ring made of Christ's own flesh rather than a typical precious metal band. The notion of this ring being made from Jesus's foreskin was mentioned by St. Catherine herself in her letters and is recorded by her biographer, Blessed Raymond of Capua. The ring symbolizes a deeply spiritual and physical union with Christ, rather than an earthly material object.