Picasso Stone is a type of marble, also known as spiderweb jasper. The stone naturally forms with geometric abstract patterns, reminiscent of Pablo Picasso's artistic style. Each set of 7 polyhedral dungeons and dragons dice comes with a padded case with a display window. All stone/fossil dice are handcrafted, and spin-tested and calibrated for precision and accuracy. Please roll your stone dice on a padded surface to protect them and your table. Due to the natural material of the fossil/stone, the exact coloration and pattern will vary.