Approximately 1.5 inches. 
Picasso jasper is said to make for an excellent meditation stone. Some people value Picasso jasper for its ability to renew lost friendships or to help guide during relationship transitions. This stone is said to promote inner clarity and interpretation of one's own thoughts.Has strong, calming, and grounding energies. It will boost your creativity, personal strength, and sense of self-discipline. It's also believed that it can assist in improving or transforming different aspects of your relationship.