Gem
From ErfWiki
Canon
A gem is a physical object which can be converted directly to Shmuckers by a caster, warlord or ruler. Shmuckers cannot be made into gems, except by a Moneymancer.
Speculation
Gems are the primary means of Shmuckers being hidden from a Moneymancer.
Gems are a way to make illicit payments from one side to another.
