These coasters are guaranteed to be one of a kind! Each piece is a ceramic tile, painted with acrylic, then sealed with a KS Resin Liquidstone countertop epoxy. This makes them heat resistant and water resistant and perfect for holding your glass. Can also be used as decoration, a soap holder, or anything else you can imagine! Each piece is finished with a back of cork to protect tables. This is a 4 piece set of coasters; each piece is 4.25in x 4.25in.