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thecatsmeowcollectibles · ‎08-30-2025

Hello Fellow Jewelry Buffs & Sellers, Is Presidium the only machine made to test for gemstones (all, not just diamonds)? Seems as if they have the market covered. It's a bit too costly for me, and I wanted to ask if any of you use any of these types of machines? Any other manufacturers or any advice is appreciated. Thanks!!

jklfindings · ‎09-01-2025

Presidium is the only one to my knowledge, and we use one daily. It's pretty handy, but I would not recommend it to anyone who doesn't already have a wealth of gemological knowledge. It's really just a shortcut tool for gemologists, and not a magic wand like most think it is. What it's handy at doing is quickly giving you a better perspective on a stone. For instance, if a light blue stone walks in, it will most likely be aquamarine, or topaz, and the Presidium will easily differentiate between them. But it could also be sapphire, tourmaline, spinel, etc. Several of those are going to cross over other readings, so if you don't know how to separate those choices out, you're not really identifying, your guessing. If you are truly trying to learn how to ID stones, start with a refractometer and a polariscope.

idealgems1 · ‎09-02-2025

I'm a Graduate Gemologist who has never owned or operated a Presidium. But I would wholeheartedly agree with @jklfindings. From my understanding, the device gives you an indicator, not a determination. There is really no shortcut to gemological knowledge; it is gained through education, experience, and the right tools.

Not counting a binocular microscope, a refractometer is the first go-to tool of any gemologist. A polariscope will provide a quick and easy way to sort LOOSE singly refractive vs. doubly refractive vs. amorphous gemstones once you have the RI reading down, helping to eliminate certain stones as possibilities.

I would really suggest that the VERY first place to start is at www.gia.edu. Get yourself a base of gemological knowledge. Also get a binocular microscope with dark field illumination and get comfortable with it. Follow that with the refractometer and polariscope. You will shortly be on your way to stop guessing blindly at what gemstone it is that you are looking at!