
A refractometer is an important tool for gem identification. The Gem Lab refractometer is an inexpensive model that’s a good choice for a novice gemologist.
3 Minute Read
Editor’s note: Donald Clark wrote his review of the Gem Lab refractometer in 2006. Currently, you may find the Gem Lab refractometer (GML-501) for sale at resale shops and online marketplaces like eBay.
Although very similar in appearance to the ones I tested previously, the Gem Lab refractometer wasn’t the same. (This model appears to have the same case). This instrument has greater magnification, a built-in monochromatic filter at the back, and weighs more. Also, it has a transparent scale, whereas the others show the shadow against an opaque scale.
The instructions have been translated from Chinese into English, with a few errors. However, if English is your first language, you’ll be able to read them well enough. If English isn’t your first language, you might have some trouble. Review our series of articles on refractometers for more information on how to operate these tools.
The refractometer comes with a tiny bottle of RI liquid, a 10 gram refill, a small flashlight that fits into the back of the instrument, and a glass block for calibration. All these items fit into a padded carrying case, which itself fits into a…









When you join the IGS community, you get trusted diamond & gemstone information when you need it.

Editor’s note: Donald Clark wrote his review of the Gem Lab refractometer in 2006. Currently, you may find the Gem Lab refractometer (GML-501) for sale at resale shops and online marketplaces like eBay.
Although very similar in appearance to the ones I tested previously, the Gem Lab refractometer wasn’t the same. (This model appears to have the same case). This instrument has greater magnification, a built-in monochromatic filter at the back, and weighs more. Also, it has a transparent scale, whereas the others show the shadow against an opaque scale.
The instructions have been translated from Chinese into English, with a few errors. However, if English is your first language, you’ll be able to read them well enough. If English isn’t your first language, you might have some trouble. Review our series of articles on refractometers for more information on how to operate these tools.
The refractometer comes with a tiny bottle of RI liquid, a 10 gram refill, a small flashlight that fits into the back of the instrument, and a glass block for calibration. All these items fit into a padded carrying case, which itself fits into a…

A refractometer is an important tool for gem identification. The Gem Lab refractometer is an inexpensive model that’s a good choice for a novice gemologist.

“I have never known or heard of an organization that offers so much for its members, and at such a low cost.”
— Ernest Roisch, Rainbow Rocks LTD
That's less than $0.01 per article. Get instant access to 1,700+ premium articles, courses, and gem pricing data.