Sold by piece, sized by weight. Stones from different sizes may look similar in the pictures depending on the shape of each piece. Looks may be deceiving but weight isn't. For size reference a true to size cardboard bank card has been placed next to the stones in some pictures.
 
SM: 13-15g
MD: 20-27g
LG: 30-37g
XL: 40-50g
 
Septarian: Solar Plexus and Body energy, can help body energy relax and heal. 
 
These pictures were taken both with the stones dry and sprayed with water.