Ruby
A 2008 March survey indicated a value of 73 gold per ruby, though some tinkers collect them for crafting purposes. They are also now used for Imbuing and in miscellaneous crafting Recipes.
In the 2008 event involving The Six rubies with slightly different graphics from the 'usual' kind dropped after defeating a member of The Six. At the time these rubies could not be sold to NPC vendors, but in a later patch it became possible to sell them to NPC vendors.