Posted here is a set of 50 green glass stones from Koplow Games, the NICE DICE(R)Company. These work great for keeping track of character hit points without constantly erasing on your sheet and wearing a hole or leaving behind an ugly smudge mark. These can also be used as replacements or additions for any game that uses glass stones.
Each of these "stones" is made of green glass. Each stone is roughly 15mm in diameter (circular in shape, though not perfect circles) and 8mm tall. The base is flat so that the stones sit nicely and the top is rounded.
These come with a simple 4 inch by 5 inch black cloth bag for ease of transport. There is enough room in the bag to hold all fifty stones and about ten standard size RPG dice or fifty more stones.