The sizes of our rocks products vary slightly as a result of the more organic cutting and shaping process, the large ones are in the region of 40 x 70mm. 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. Better used (we think) when mixed with the other sizes of rocks.  Shown with 23mm cube for scale - not included.