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Presidium Gem Tester II! Everything you need to know - Review

Updated: Oct 28, 2022

Welcome to my second official review of Presidium Instruments since the announcement of our collaboration in early May 2022. (LINK TO BLOG)


I’ve been using the Presidium Gem Tester II for the last week on many of my gems at home and I did get some surprises.

Most of my gemstones are purchased from reliable sources and they come with authentic gem reports, but we have all purchased gems online for a fantastic price and wondered - Are they really what they are supposed to be? Having the Gem Tester II is a perfect way to find out. So let me take you through the benefits of using the Presidium Gem Tester II

What is the Gem Tester II used for?

Presidium Gem Tester II (aka PGT II) provides a quick and easy way to identify Diamonds/Moissanites and separates up to 16 of the common-coloured gemstones based on their thermal conductivity with its clear and direct analogue display. A newly redesigned inbuilt calibration reference and adjustment provides ease of operation both indoors and outdoors.


  • Retractable thermoelectric probe tip that ensures constant pressure between probe and gemstone

  • Industry’s thinnest probe tip (0.6mm) for testing gemstones as small as 0.02 carats

  • Metal alert buzzer to ensure probe tip is in contact with gemstone during testing

  • Tests both polished and unpolished gemstones

  • Clear and easy-to-read analogue dial

  • Can differentiate between 16 types of gemstones

  • Built-in Glass and Calibration (CAL) test discs for reference

  • Can be used with a battery or plug-in adaptor

*Does not differentiate between natural and synthetic coloured gemstones but a little more about that later on this blog.

PGT II Image Gallery

Who can benefit from using this tool?

Jewellery Valuers

Bench Jeweller

Jewellery Professionals

Independent Jewellers

Pawn Brokers

Gemmology Students

Gem enthusiast

And anyone that is a bit of a Gemmology Obsessed 😊

The biggest sector in the jewellery industry that will benefit from using the PGT II is independent jewellers that purchase second-hand items from clients. More often than not you will have to send the item for Gem identification which will take at least a few days, just to come back and turn out to be a white sapphire rather than a Diamond. With the Presidium Gem Tester II you will be able to tell and potentially use the tool in front of the client for successful identification of their gems. Once successfully identify the Gems, you will be able to accurately calculate the price of the items and give it to your client within a few minutes of them walking into your store.

We all have wondered is it a Topaz or is it an Aquamarine? Is it a Ruby or Red Spinel? The PGT II is able to determine within seconds which one is secretly the more expensive one 😊


Why this Gem Tester?

The Presidium Gem Tester II features the industry’s thinnest retractable probe tip (0.6mm) for testing coloured gemstones as small as 0.02 carats. Coated gemstones can also be generally tested with PGT II.

*Does not differentiate between natural and synthetic coloured gemstones.

Synthetic Coloured stones are a bit more tricky to identify, they tend to be more clear in terms of Clarity due to the lack of inclusions, unlike most natural stones. Another good kit for you to have is the Presidium Refractive Index Meter II

By measuring the quantity of light reflected through the stone, the Presidium Refractive Index Meter II is able to separate Diamonds, Moissanites and other coloured gemstones via the Refractive Index (R.I) of these polished gemstones. No need for messy R.I liquids! The PRIM II can separate Synthetic Sapphire, Synthetic Moissanite, Synthetic Emerald, Synthetic Spinel and many more natural coloured stones.

Hopefully, I get to review this tool and show you how fascinating the world of gemstones really is.



Power & Battery

2 x AA alkaline batteries (approximately 3 hours of continuous use)

AC port to be used with appropriate Presidium Power Adaptor (included)

Recommended Operating Conditions

Optimal Operating Temperature: 18°C – 27°C (65°F – 80°F)

Storage Temperature: 10°C – 51°C (50°F – 124°F)


Length: 125mm (4.93 inches)

Width: 90mm (3.55 inches)

Height: 70mm (2.76 inches)


Weight (without batteries): 220grams (7.76 oz)


How much does it cost?

Retail Price - SGD $379.00 (Approx. GBP £218 – EUR €257 – USD $275 – Currency date 26/05/2022)



Thank you very much for reading my review on the Presidium Gem Tester II, please let me know if you have any questions. I’m always happy to help