Pure gem
A pure gem, otherwise known as an orb gem, is simply any gemstone which has been found or created from a normal gem using Purification Song (1004), in a purified state.
Such gems can be rather valuable in monetary terms since they can be used as a material component in many advanced spells. These include Holy Receptacle (325) and Charge Item (517). In some cases, particularly with Holy Receptacle, the monetary value of the gem may affect the outcome or effectiveness of the spell.
They may also be imbeddable with the use of grot t'kel potion.
The easiest way to identify such a gem is to have a bard attempt Purification Song (1004) on it; if it is already pure, no further purification is possible. They can also be identified by loresinging or by attempting to use them as a spell component. Phase (704) can also be used to find an orb gem. Only a pure gem will phase when cast upon.
All tiny pearls are natural orb gems.