Handcrafted tumbled stone coasters by Studio Vertu. Each coaster is handcrafted by trained artisans in the USA. Due to the use of natural stone, variations are to be expected, and enhance the unique beauty of each tile! To clean, use a damp cloth and wipe clean. Do not use any harsh chemicals or abrasives. Dimensions: 4x4 tumbled Botticino marble. Corked backed