Hand-formed glass, flattened into several shapes - triangle, round, long and oval.
There are 6 opaque colors and various sizes. Basically, these pieces are either small, medium or large, but as each one is blown and then hand-formed, the ultimate sizes vary. The round stones, which are the most uniform in shape, are approximately 7" in diameter - small, 9" diameter - medium, and 11" diameter - large.
There's a small hole in the center back of each stone and a nail at an angle in your wall is all that is required to mount the stones.