Someone you should definitely talk with is Jorge Caridad, owner and general manager of Ambar Nacional, AMBASA in Santo Domingo. He has recently moved (needed more space for his outstanding amber museum), but retained his old location as his workshop for jewelry making.
Should have mentioned that Jorge Caridad speaks English.
I just took a closer look at the web pages on the two museums. There doesn't seem to be an email address for him. The telephone numbers are 800-682-3309 and 809-686-5700. Fax is 809-688-1142