How To: Gemstone Testing

When working with gemstones, quality assurance is always a top priority. Extensive testing must be done to ensure the quality of the gemstones that you buy and sell.

Here we will share with you some of the techniques and tools that will help you sell with confidence.

Key Instruments Used:

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

Inspect

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

Refractometer

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

Step 3

Polariscope

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.

Tester	What 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 Meter 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;

EXTENDED CONTENT:

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)

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