The study of gemology can vary from tedium to astounding
revelation. Mostly it's boring ... especially at first.
Partly because you don't have a clue about what you're
reading.Then a glimmer of understanding reaches out toward you and you really begin to understand refraction or dispersion.
Be careful ... since at that point you may be hooked. Next comes the desire for refractometers and microscopes and begging anyone for gems to study.
If you start to develop a more keen interest in gemology, start studying minerals. After all, gems are merely optically appealing specimens of minerals that have mundane uses in their common form.
Garnet, as an example, was once used as the grit on sandpaper.
If you want a more formal approach to gemology, several community colleges have excellent programs.
Find and join your local gem faceter's club. A good cutter has to know quite a lot about gems.