Geologists specializing in precious stones and minerals? Does that exist? And what job title is it?

I took a PhD in mineralogy and MSc in crystallography. I spent the first few years involved with overseas mineral prospecting before I became a professional gemmologist (UK spelling of gemmologist). I have spent the last 40 odd years identifying, buying, selling and collecting precious stones specializing in rare items for museums and collectors around the world. I have enjoyed every moment so far and I am sure there is even better to come. I wish you all possible luck in your career choice and hope that when you are qualified you will join the small band of professionals in this field.