Key Instruments Used:


Item #:56-7709:


Item #:26-2603

Binocular Microscope

Item #:26-4073

10X Power Loupe

Item #:29-2606

Testing Tips:

Testing Tips:

  • Make sure the stone you are inspecting is clean and polished.

  • Always clean the probe tip by running it back and forth across a sheet of paper.

  • Test at room temperature.

  • Hold tester perpendicular to the table of the stone.

Step 1


Using a 10x Power Loupe inspect a clean and polished stone with the unaided eye. Observe for color, transparency, cutting style and any unusual phenomena.

Step 2


Next, use the Refractometer to obtain a reading of the gems refractive index.

Step 3


Then use the Polariscope to find out if the gem is singly or doubly refractive. This is the optic character of the gem and will help identify the material of the stone.

As you move the stone around you are looking for any changes in light or any blinking.

Step 4

Binocular Microscope

Use the Binocular Microscope to look deeper into the stone for any unusual characteristics. These unique inclusions act like fingerprints to easily identify certain gems.

Step 5

Gem Property Chart

Finally, take all the readings and compare them against a Gem Property Chart to find an exact match.

Passing the Test

Gemological Testers

Staying informed is a vital part of success in our industry and knowing which gemstones you’re working with is critical. To help, below, we’ll break down some of our newest and bestselling testers and give you some insight on function and use.

TesterWhat does it detect?Why is it a must have?

Gemlogis Lapis One
Diamond, Moissanite
(including Forever One),
Simulant, and Metals
Uses “visible violet light”
technology to detect Forever
One Moissanite

Gemlogis Ciel One
Diamond, Moissanite
(including Forever One),
and Simulants
Works seamlessly with
Pistachio Referential
to indicate a variety
of popular gemstones

Sam by Presidium
Diamond, Moissanite (including “low electrical conductivity Moissanite), and Simulants Connects directly to PC via
OMI software for a direct recording of results that can easily be sent to customers

GemOro Testerossa

Diamonds, Moissanite (including Forever One), Sapphire, and gives Metal Alerts Programmable talking voice
alerts in 9 languages and
can be calibrated

Adamas by Presidium

Diamonds (including melee), Moissanite, and gives Metal Alerts Includes changeable tips,
which allows immediate replacement of any worn
or damaged tip

Presidium Synthetic Diamond Screener
Screens for synthetics or lab-grown diamonds (both CVD and HTHP) More cost effective than
most synthetic diamond screeners

The PhosView
Screens for synthetics or lab-grown diamonds (HTHP only) Screens melee and mounted stones

And we can’t forget about colored gemstones. This is the Presidium Gem Indicator, the only handheld tester in the industry designed specifically for colored stones. It indicates up to 31 different types of colored stones. 56-7903;


To learn more visit our gemological center

We're always here to help. For technical questions call 800-877-7777, ext.540 (Diamonds) or ext.546 (Gemstones)