See if a company is giving you a opportunity without a course then you should do it. If you have good understanding and knowledge you will obviously prosper in the field. Internships helps to create contacts as well as gives you an opportunity to apply your knowledge in the real world.

If you want to know about the Gemology Course then you can visit the link provided below:

https://www.careers360.com/courses/gemology-course

I hope this answer helps. All the very best for your future endeavors!