Wonderstone is a gorgeous material that often has multiple colors (generally sunset like colors) that tend to form a wavy bullseye like pattern, which is believed to have been formed through the osmosis of water within the stone as it was forming. It tends to work into some pretty neat cabochons, and it really became a well known old time stone due to its endless possibilities!
Measurements (inches - longest - approx): 4.2 x 2.6 x .34
The last photo has been taken dry so that you may see any defects. The other photos have been taken wet to simulate a polish.