A staff member from the state-run Myanmar Gems Enterprise displays a 36-carat ruby worth half a million euros.Burmese rubies generate about $500 million annually. They account for over 90 percent of the global ruby trade. The U.S. bans the rubies because profits benefit Burma’s military junta. But as the junta initiates reforms, observers wonder how long the sanctions will remain. David Mathieson is senior researcher on Burma in Human Rights Watch’s Asia Division. He’s based along the Thailand-Burma border, where he works on various issues related to military rule and repression in the region.  Christian Holst is an award-winning photographer whose work depicting Burma’s ruby trade is on display at the Field Museum through May 13. The two discuss Burmese rubies and the country’s future in international trade.