The AGTA American Gem Trade Association puts out a book of all their members, what they sell along with all important information about each vendor. If you are not a member or listed with JBT or Dunn and Bradstreet then you may have to pay with a credit card in advance. But you will find dozens of vendors that sell tanzanite and some that specialize in it. If you really want to get to know these people and earn their trust along with finding the best prices on colored stones then you need to spend the time and money to attend the Tucson gem show in February. You better call for a room now if you want to go. Hotels rooms become scarce and expensive.