Since early 1989, a gem dealer I've known for years has been calling me every few weeks to brief me on mounting mayhem in Colombia's lucrative emerald market. The troubling gist of these calls is always this: There is a full-fledged turf war going on between that South American country's bustling drug and gem trades for control of its emerald ex port business. According to this dealer and several others, anywhere from two to four thousand emerald industry people, mostly miners and deal ers, have been murdered since 1980. No doubt the gem sector, itself never gun shy, has retaliated in full...