How do you use the reset stone in dragon quest IX

It's an alchemical component for use in the alchemiracle recipes, and a few others. For example, Meteorang upgrades to Asterang. Once you try to alchemise Asterang and the required components together, you'll probably get Stellerang, but there's a chance you'll get the rarer Galaxarang. However, you can alchemise Stellarang and a Reset Stone together to get a Meteorang again, so you can try again for the best upgrade.