The sizes of our rocks products vary slightly as a result of the cutting and shaping process, the small ones are in the region of 25 x 35mm. They represent clear ice that has been picked rather than hewn from a block of clear ice. They offer a much more random appearance, and the chance for much stronger refraction of light through the glass. Beter used (we think) when mixed with the other sizes of rocks. Shown with 23mm cube for scale - not included.