Spell gem

Spell gems were magical gems created by svirfnebli.

Description
The function of such gems were to store single spells. Specific types of gems could store more powerful spells. Unlike typical spells or scrolls, anyone could cast a spell stored in a spell gem. However, the more powerful the spell stored was, the more difficult it was to cast it. The whole creation process was kept secret by the svirfnebli.

Variations
There were several types of gems that could store spells. In order of the power of spells they could store, the gems were:
 * Obsidian (cantrips only)
 * Lapis lazuli
 * Quartz
 * Bloodstone
 * Amber
 * Jade
 * Topaz
 * Star ruby
 * Ruby
 * Diamond