The Stone must be in the Alchemist's inventory before a transmutation can be performed, and is not consumed by the transmutation. Most transmutations have a long cooldown (20 hours). Multiple Stones do not allow an Alchemist to perform more rapid transmutations.
Patch changes
Patch 2.4.3 (2008-07-15): Skill requirement reduced from 225 to 200.
Patch 2.4.0 (25-Mar-2008): Made a Level 35 trinket, and +5 stat bonuses added.
Patch 1.2.0 (18-Dec-2004): Effects have been changed.