Tumble stone sizes generally range from 1 - 3cm
Serpentine (Peru) Tumble Stone
Serpentine stone has a strong energy known to stimulate the arousal of the kundalini energies. If you feel that there may be blockages in any of your chakras, this stone is a useful aid. ... This green stone may assist with healing problems within the heart and lungs, and it is an excellent stone for cellular regeneration.