If you are going to do any diamond grading, you will want exactly
10X, as some of the grades are based on what can be seen at 10X. You
would probably also want a higher magnification, say 20X or 30X for
looking more closely at inclusions and striations. There are a few
gemological uses for magnifications as high as 60X, but I cannot at
the moment remember what.
Most of what you do can be done with 10X and 20X. If you can get a
microscope with two sets of objectives for the two powers, you can
then get a set of 20X eyepieces to replace your 10X ones and double
You need to remember that lighting is as important as magnification
and you really need to try to get a microscope with darkfield
illumination, as it is so useful for seeing inclusions. Many
microscopes have it built in. If yours does not, you can use fiber
optic illumination to duplicate it. You may be able to find two of
those small LED lights on flexible arms to more or less duplicate
fiber optics. I have not tried this, but they look like they would
work pretty well. You can get these in the Dollar Store, so it is
really lighting on the cheap. You would need some clamps like a
third hand to position them, or perhaps a little weighted base in
which the battery cartridge of the light would fit.
You could actually use a good 10X loupe for a lot of your ID and
grading work and possibly use one of those cheap 30x hand microscope
for more magnfication. There is also a dark field magnifier that look
like a flashlight that many use in the field. It really is good to
develop your skills with a loupe, as most of us do not have a
microscope in our portable lab and make do in the field with a loupe
and a few other instruments.
Microscope sure make the job easier and are great fun to look
through, but you need to give some thought to what other instruments
you feel you need.
A spectroscope is a good thing to have, a polariscope with a
strainless sphere and quartz wedge substitute allows you to determine
optic character and sign and a dichroscope is also good to have. not
to mention the Chelsea filter and maybe a set of the other Hanneman
filters. You could probably get most of this stuff for the price of a
microscope and do without it for a while. A refractometer might also
be something you’d want to consider before a microscope. And a
portable UV light.
What you buy may be determined by what approach to ID you take. Many
never use optic character and sign, but they are a great help and the
instruments are very portable. If you fool with rough and unmounted
stones a lot you may want to have a specific gravity balance. This is
really such an interesting and complex subject that doing some
reading before buying much would be a great help. I’d recommend
Antonin Maitlins’ book and Hanneman’s Affordable Gemmology, if you
can find it.
Good luck on a fascinating journey!