Among many gem labs, the one best gemological lab I personally trust with my order is GSI. You can check on https://gemscience.net/
for contact details. I appreciate their approach towards work with professionalism, integrity and accuracy as their priority. They not only just focus on grading gemstone but on gemstone reporting, gemological research and consumer protection initiatives. They offer an unmatched variety of products and services and promote communication and education programs for both the trade and consumers.