THEOBROMA set of 4 concrete coasters | concrete coasters | concrete coasters | concrete coasters | concrete trivet. Dimensions: 9 cm x 9 cm x 1 cm (height) Materials: water, non-toxic pigment, concrete. Note: Because all the pieces are handmade and because of the nature of concrete, no two pieces are exactly the same. Each piece has slight variations (i.e. air bubbles and color). No concrete casting is 100% free of bubbles/blemishes, but that adds to its charm and character!