Mother of pearl rings

Nacre

— initially, mother-of-pearl is the material from which pearls are formed (see the relevant paragraph). The key difference is that the pearl is necessarily round, and the shape of the mother-of-pearl insert can be any. The same goes for her colour. For a number of reasons, this material is extremely rarely used “alone” in rings — it is usually found in richly decorated items and serves as an addition to other precious stones, often quite expensive.