Presidium Gem Tester / Colored Stone Estimator (PGT/CSE)

A light and portable instrument that instantly identifies diamonds and most colored gemstones based on their thermal properties.

Presidium Gemstone Tester / Colored Stone Estimator is the only colored gemstone thermal tester in the industry. It provides a quick and easy way to identify diamonds and separate common colored gemstones from one another based on their thermal conductivity. Coated gemstones can also be generally tested with the PGT/CSE.

The Presidium Gem Tester / Colored Stone Estimator has a retractable probe tip that ensures consistent pressure against the gemstone during testing for more reliable results. With the industry’s thinnest probe tip size of 0.6mm, PGT/CSE tests diamonds as small as 0.02ct.

*Does not differentiate between natural and synthetic colored gemstones.


  • Retractable thermoelectric probe tip that ensures constant pressure between probe and gemstone
  • Industry’s thinnest probe tip (0.6mm) for testing diamonds as small as 0.02ct
  • Metal alert buzzer to ensure that probe tip is in contact with gemstone during testing
  • Clear and easy-to-read analog dial
  • Multi-colored gemstone display
  • No waiting time between tests
  • Built-in diamond and simulant test discs for reference
  • Powered by 2 x AA batteries or adaptor
  • Leather carrying case included
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Built-in test discs
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Easy-to-read analog display

Dimensions and Weight

  • Length: 165mm (6.5 inches)
  • Width: 77mm (3.03 inches)
  • Height: 77mm (3.03 inches)
  • Weight: 260g (without battery)
  • Weight: 272g

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  • Identifies diamonds and most colored gemstones
  • Tests both polished and unpolished gemstones
  • Tests gemstones as small as 0.02ct
  • Consistent and reliable results every time
  • No waiting time between tests
  • Clear and visible display for ease of reading measurements
  • Simple and easy to use
  • Light and portable tester that can be used anywhere

Power and Battery

  • 5 x AA batteries (approximately 4 hours of continuous use)
  • AC adaptor 120 / 230 volts (standard item provided by Presidium)

Measurement Range

  • 0.02 carat and above

Operating Conditions

  • Operating temperature: 18°C-27°C (65°F-80°F)
  • Storage temperature: 10°C- 50°C (50°F-122°F)

Package Contents

  • Presidium Gem Tester / Colored Stone Estimator
  • Probe pen
  • Colored gemstone display
  • Built-in test simulant discs
  • AC adaptor
  • User handbook
  • Warranty card
  • Leather carrying case
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Probe pen
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Additional Information