By Mark T. Cartwright
Every professional has tools and techniques they consider indispensable to their trade. The world of gemmology and jewellery appraisal is somewhat unique in that many of us are left to figure these out for ourselves.
One of the many great things about belonging to a variety of organizations is the ability to learn from more experienced peers with different backgrounds and training. Some of us have or have had mentors to guide us, sharing the various tips and techniques they’ve learned over the years; some of us have been fortunate enough to find ourselves the mentor. I feel a special obligation to my teachers to pass along some of the things I’ve learned that I consider a vital part of my practice. For some readers, this will be new information, for others, perhaps not. I don’t claim to have originated any of the things I’ll be sharing, and if I present these ideas poorly, I trust my teachers will excuse my lack of art.
Although deep within the emerald, the yellowish-white fluorescence caused by the near-UV laser’s intense beam can reveal the extent of ‘oiling.’
Dark-field illumination—a standard clarity grading environment for diamonds—can have some limitations when dealing with highly dispersive stones and low-relief inclusions.