The AGATE SLICE COASTER can be found in large and substantial form naturally. Large agate slices are used to make stunning furniture, such as tables as well as various crafts. In the process of creating agate gemstones, the rough agate is sliced and polished to form smaller stones of varying carats. Agate Slice is a type of semi-precious stone made of chalcedony and comes in a large range of colors. All agates feature bands of colors with only a few exceptions.