Mother of pearl earrings

Nacre

— mother-of-pearl in this case, in fact, is a “simplified version” of pearls: if a pearl necessarily has a complete spherical shape, then a mother-of-pearl insert is, roughly speaking, a plate. The shape and dimensions of such a plate may be different, it may have round or figured contours, be flat or convex, etc. The advantage of mother-of-pearl over pearls is that it can be made brighter and given an original shape. The properties of these two materials are similar, see "Pearls" for more details.