Natural Stone Coaster with Red Crest (Coaster-1) Absorbent round natural stone coaster, 4.25" diameter with cork backing. Adorned with the School of Natural Resources name in a crest design. These stone coasters provide a protective barrier against water rings and condensation puddles while the cork backing protects furniture from scratches and marks. Earthy feeling sandstone is absorbent and good looking. Value priced, no additional discounts available.