Shell

Two coastal placemats: the Shell Placemat and the Reef Placemat.

Shell has a natural iridescence that shifts color as you move, so it is neither the single sheen of a pearl nor the point-flash of cut glass. That in-between quality is why shell works on a table meant to look dressed without looking formal: a lunch table, a porch, a summer dinner. It also sits with the blues, sand tones, and raw wood a coastal room usually already has, where rhinestones would fight them.

Keep the rest of the table quiet and let the mat be the texture. For more shine in the same warm register, the metallic beaded mats are the next step up.