Go to any hive of drinkers and gamblers in the Marches and you will undoubtedly hear the legend of the Gem of Keroshek. Ask three different men about it and you will get three different stories. One will say that an alchemist found it in the ashes of Andraste's pyre and then steeped it in wine for forty days and nights. Another will swear that it was a bezoar cut from the belly of a boar that was found inside a griffon that was swallowed by a high dragon. The last will tell you that it's the petrified heart of Trajan the Quick, a merchant prince of Orzammar who almost became a Paragon.
One thing all will agree on, however, is that it brings luck. Keep the Gem of Keroshek in your pocket and you will never lose a bet. Sleep with it under your pillow and it will bring wealth and prosperity into your life.
And where is the gem now? That is the sovereign-plated question. I'm told it's in the mausoleum of a prince of Starkhaven, and that this is the reason for the city's wealth.