Smithsonian One-of-a-Kind Agate Coasters Make a conversational splash with these showstopper One-of-a-Kind Agate Coasters Made of genuine agate&mdash;a semiprecious stone that the ancients believed would guard against danger&mdash;the One-of-a-Kind Agate Coasters for each set are selected for their shape, pattern and translucency and enhanced to maximize their rich colors Happily, each will vary in size, shape and color, making your set truly unique Assembled in the U.S.A. with rubber feet on the underside. Approx. 4.5"dia. Set of 4.