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Gem-n-Eye RI Meter Gem Tester DuoTester Refractometers Gem Filters ComputerGauge Dichroscope


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Our selection of Gem ID Tools are summarized below.  Click on the pictures or hyperlinks below, or the navigation buttons above for detailed descriptions, or to order any of these products.

Gem-n-Eye Digital Refractometer

A Digital Refractometer that uses the reflectivity of Faceted gemstones to confirm their identity.  It gives a digital readout in the form of a Refractive Index to 3 decimal places, along with the Gemstone names that share that RI value!  The Gem-n-Eye covers the entire R. I. range, from Glass and Colored stones, thru Diamond and it many simulants.  Use with Loose and many Mounted stones.  The Gem-n-Eye has an internal database of over 200 gemstones, and also functions as a Gemstone Computer, performing a combination search of 9 key properties of a gemstone to aid in identifying it.

Price: $425

Presidium Refractive Index Meter II

An advancement over, and ultimately replacing Presidium's original Reflectivity Meter - Presidium has converted the digital readout to an actual RI value displayed to 3 decimal places.  This meter comes with USB connectivity and computer Software that includes a Gemstone Database, Lookup and Property Search functions.  The PRIM II is for use on Faceted stones only, and covers both the Colored Stone range as well as High Index stones.

Price: $279


Presidium Gem Tester/
Color Stone Estimator

This instrument is like a thermal conductivity probe as historically used on Diamonds, but now engineered for use on Colored gemstones, with an analog meter readout where the needle points to the identified gemstone(s) species.  It works on Loose or Mounted Faceted stones, but unlike the Reflectivity meters, can be used on Cabachons as well, along with Gemstone rough.

Price: $219


Presidium DuoTester

The DuoTester combines the features of the Reflectivity Meter and the Gem Tester into one instrument, measuring both Reflectivity and Thermal Conductivity.  It is the only tool on the market that provides the user with two proven tests for Diamonds and the ability to differentiate between similarly Colored gemstones.  Can be purchased with or without a set of seven species of faceted Diamond simulant gemstones.

Price: $349 to $449


Gemological Refractometers

The standard gem ID instrument, used to measure Refractive Index and Birefringence of gemstones up to 1.81 R.I.  The Refractometer is known for its accuracy and consistency.  We offer 2 models to choose from, Professional and Economy grade, along with Refractive Index Fluid.

Price: $595


Gem Filters

A simple and affordable tool for separating many Colored gemstones.  These filters are designed to transmit only certain colors of light, so when the user looks at a stone through the filter, he or she observes the apparent color of the stone and matches that up with the identifying chart that comes with the filter.  We offer 4 different filter selections, including the renowned Chelsea Filter.

Price Range: $28 to $64

Presidium Gem Computer Gauge

Incorporates a precise digital calipers to measure the size of a gemstone, adds to that your input of the type of gemstone cut, and uses that data to estimate weight.  Or, if you provide the weight of a stone, this tool will also estimate specific gravity, and retrieve matching gemstones from its internal database, and thus aid in identifying unknown stones.

Price: $249

Calcite Dichroscope

Use a dichroscope to determine Dichroism and Pleochrosim of gems as an aid to identify them.

Price: $69

Buying Guide to Refractometers versus Reflectivity Meters:

A Refractometer measures a gem's Refractive Index (R.I.) and Birefringence, the former by essentially passing light through the stone, and where that light refracts out at a defined and consistent angle based upon that gemstone species' makeup.

A Reflectivity Meter essentially bounces light off the surface of the stone, measures that degree of reflectivity or luster, and converts that into a readout.

Pros and Cons:

Refractometers are accurate and consistent, and therefore the first instrument of choice among professional gemologists.  However, they require the use of R.I. Liquid which is smelly, potentially toxic, and a little inconvenient.  Furthermore, almost all refractometers have a maximum limitation of 1.81 in R.I., thus excluding high index stones like some Garnets, Zircon, Diamonds, and various Diamond simulants.  So in effect, Refractometers cover mainly the range of so called Colored Stones.  It should also be said that advanced gemologists can use Refractometers to measure some cabochons, in addition to faceted stones of course.

Reflectivity Meters are less accurate and consistent than Refractometers, leading to more overlap among possible gemstone species, and therefore requiring secondary tests for reliable identification.  Having said that, Reflectivity Meters are fast and easy to use, and require no messy liquid.  Furthermore, they have no limitation on the range of stones - they can measure anything from lowly glass all the way up to and through Diamond and its simulants.  Reflectivity Meters can be used only on faceted stones.