Category: Colored Gemstone Testers

Refractive Index Meter II

SGD $409.00

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The Presidium Refractive Index Meter II is a desktop digital tester for the accurate measurement of broad-range R.I. values, from 1.000 to ~3.000

Desktop digital tester that uses refractive index to quickly separate gemstones, diamonds, moissanites and other diamond simulants.

By measuring the quantity of light reflected through the stone, the Presidium Refractive Index Meter II (PRIM II) is able to separate diamonds, moissanites and other colored gemstones via the Refractive Index (R.I) of these polished gemstones.

Unlike a traditional refractometer that has a limited range of R.I measurements and thus cannot be easily used to measure R.I of certain gemstones, the PRIM II is able to measure a wider range of R.I value from 1.000 to ~3.000, therefore covering the commonly known gemstones in the market and can also measure RI of diamonds, moissanites and other diamond simulants such as high zircon, strontium titanite, etc.

In addition, a fast and clean test can be easily done with the PRIM II, without the inconvenience and messiness of R.I liquid used in the traditional refractometer.

The PRIM II also comes with a downloadable software that provides a database of more than 50 gemstones with their various properties and possible origins, and a program that enables the user to enter known properties of the gemstone such as color, S.G. value, hardness, etc to ascertain what possible gemstone it is from the database information.


  • Pinhole-sized light reflectivity measure on wide oval platform
  • Cover cup with blackout interior to ensure light reflectivity measure is accurate
  • Instantly displays direct R.I reading on digital index LED display panel
  • In-built Refractive Chart for referencing diamonds and simulants above R.I reading of 1.8
  • In-built 8-piece gemstone holder
  • Pocket-sized Refractive Index Chart pull-out with R.I readings for 55 stones
  • PRIM II complementary software to help users find out the possible colored gemstone using data on various gemstone properties
  • Gemstone Dictionary in software with 57 gemstones’ properties (R.I, Color, Hardness, S.G. Value), country of origin and related information
  • USB port for alternative power source and connectivity


  • Estimates diamonds, moissanites and gemstones’ R.I instantly, thereby allowing identification of possible stones
  • Able to test wide range of R.I values from 1.000 – 3.000, more than traditional refractometer
  • No need for messy R.I liquids
  • Tests on transparent gemstones, with flat polished surfaces
  • Continual elimination of possible gemstones via software program through input of known values such as R.I, color, hardness and S.G.
  • Ideal for separation of gemstones
  • Clear and visible display for ease of reading results
  • No waiting time between tests
  • Simple and easy to use
  • Light and compact tester
  • Runs on batteries or with recommended Presidium AC adaptor


Power & Battery 

1 x 9V alkaline battery (approximately 3 hours of continuous use)

USB port to be used with appropriate Presidium Power Adaptor (not 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)

Dimension & Weight

Length: 140mm (5.50 inches)

Width: 80mm (3.15 inches)

Height: 33mm (1.30 inches)

Weight (without batteries): 140grams (4.94 oz)

How It Works