This beach themed coaster set is made of ceramic stone which works better than sandstone. It can absorb water or drink stains more quickly and keep table dry and clean.The marble design ceramic top on these cute coasters help capture moisture from ice cold drinks and protect surfaces from hot coffee cups, more absorbent than sandstone coasters.The back of the coasters is cork to prevent table from worn and scratched, and also provide additional gripping to the land, stick to the desktop tightly , easy to handle bump and drop.This is a proper size for drinking glasses, coffee cups, white wine glasses, tea cups, or any other average sized glass.Spills can be easily wiped off with a damp rag and should not stain if removed in a timely manner. Use warm water and a mild dishwashing detergent or stone safe surface spray to clean.