Gem
Gems are high-risk, high-profit commodities intended for traders and found on the Midnight Ocean. Every capital island buys a different type of gem, depending on which archipelago in which it is located (i.e. Emeralds would be bought by the Epsilon market; Diamonds would be bought by the Alpha market, and so forth). Various times a day, some gems will spawn randomly at one colonized capital island. The sell price depends on how far you must sail them to their capital island; for instance, Emeralds would cost less at Eta Island than at Alpha Island, becaue Eta is farther away from Epsilon than Alpha is.
Traders may buy the gems and sail them to the capital island, but there are risks. If you abandon your ship for over fifteen minutes, with gems in the hold, they are stolen by mysterious forces, never to be seen again. The sea holds its risks as well, for twice the normal amount of gems are pillaged if you lose a sea battle.
Gems may not be sold to shoppes.
Gems may also be foraged from uncolonized islands, though this is a rare occurence.
Historical Notes
Gems were made a forageable commodity with release 2004-12-15.
Gems were introduced to the game with Beta release 2004-11-13.
Special gems (named after a non-existent archipelago) have occasionally been used as special event commodities. Because of this, it is possibly (but very rare) to win a unusable gem from brigands.