I use Boston Findings and Gems. 333 WASHINGTON ST. RM. 543, BOSTON,
MA 02108 U.S.A. 617-742-9402 or 800-225-2436
They have excellent merchandise and carry some calibrated stones as
well. Helpful, knowledgeable , pleasant staff. The owner, Barbara
Lawrence, is on the board of the American Gem Trade Association (that
speaks volumes!). I believe they sell wholesale only to those who
have a tax#. No financial interest here- it’s just delightful dealing
with a company that I trust and respect. Have a delightful day!