Gems
From Unofficial Ansalon Wiki
Gem values are as follows:
Garnet: 1,300 Pearl: 1,500 Opal: 2,200 Emerald: 5,100 Ruby: 7,200 Diamond: 10,000 Star Diamond: 1,000,000
Gems can be used as a light-weight currency (sell [type] to get quick cash). They can also be used to charge staves for that boost mages love. You can do anything you can with coins, with gems: Drop 3 emeralds, get 4 opals pile, give ruby Joe etc.
Star Diamonds do NOT stay on your corpse, they go back to you, period. These are the currency of building and can not be stolen/looted etc.
To see your current supply of all gems, type WORTH GEMS.