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Gem-n-Eye Digital Refractometer

  • Product Description

    For confirming the identity of unknown gemstones, brought to you by Mineralab.  The Gem-n-Eye III is fitted with an eye-catching, easy-to-read OLED display, and was internally upgraded with advanced processing capability for greater  precision in measurements.  It still is built around a 21st Century grade Light Sensor offering greater accuracy and repeatability on top of a precision calibration scheme.

    How does it work?

    Unlike a traditional critical angle refractometer, the  Gem-n-Eye requires no toxic fluid, and  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 does this by measuring Reflectivity, a property closely related  to Refractive Index, and through a sophisticated algorithm, converts that to a  familiar Refractive Index value, and then conducts a lookup within its internal  database to find and display the matching gem (s) - no need to convert values or  cross reference to separate charts, or plug into a computer, because the  Gem-n-Eye already is a computer.

    How do I use the Gem-n-Eye?

    Just place the stone over the optical eye of  the sensor, cover  it with the included light shield, and press a button.  You're done!  You  get a readout of the RI value and a list of those Gemstones that match - for  example, RI = 2.417; Diamond,  or for instance, RI = 1.698; Peridot,  Tanzanite.  Then push the button once more  to bring up the entire data on any one of those gemstones to assist in secondary  testing.

    What is the range of the Gem-n-Eye?

    Unlike a traditional refractometer, there is no limitation above the RI level  of 1.81.  Therefore, the Gem-n-Eye measures the full range of RI values,  between 1.300 and 3.300, from low ranging  Fluorite and Glass, then through the primary Colored Stone range, all the way up to and beyond high-index Diamond, including its many simulants such as CZ, Moissanite,  etc.  Likewise, the Gem-n-Eye can also measure certain garnets including Demantoid and high  Spessartines and Almandines, along with Zircon, that are beyond the reach of traditional refractometers.

    Which of these can I measure, among Faceted stones,  Cabochons, Mounted stones, and Gem Rough?

    Generally, the stones need to be Faceted.  More specifically, the stone must have a flat, smooth, polished surface, and lay flat on  top of the  optical eye of the sensor.  Therefore, loose faceted stones can definitely be  measured, and many faceted stones that are mounted in settings can also be measured,  even some larger ones where  the setting itself protrudes beyond the table facet of the gem.   Interestingly, some loose Cabochons will give good readings as well, but only from the back side, and only if  the  back has  been well polished and to a flat shape - otherwise cabochon testing is not reliable.  Gem rough generally is not measurable, however, certain species of gem minerals, in  crystal form, can be measured if a surface of the crystal is naturally flat and highly  polished, without striations or other surface imperfections.

    As to minimum size, the diameter of the light sensor hole is 1/32", so any stone tested must  have a table facet of at least that 1/32" across.

    What stones will the Gem-n-Eye distinguish between?

    The examples are many, but here are a few more common  situations where, within a typical color of a stone, the Gem-n-Eye can tell one  species from the other:



    Fluorite Iolite Aquamarine Topaz Sapphire Zircon


    Quartz Heliodore Chrysoberyl YAG CZ Diamond


    Glass Beryl Tourmaline Spinel Ruby Almandine


    Fire Opal Citrine Topaz Hessonite Spessartine CZ


    Moldavite Emerald Peridot Vesuvianite Tsavorite Demantoid


    Fluorite Amethyst Rubellite Tanzanite Alexandrite Rhodolite


    RoseQuartz Morganite Kunzite Sapphire YAG CZ


    SmokQuartz Labradorite Andalusite Corundum Sphene Diamond


    Danburite YAG CZ Sr Titanate Diamond Moissanite

    How accurate is the Gem-n-Eye?

    It is still not as precise or consistent as a traditional critical  angle refractometer, and it does not measure birefringence.  Because  the Gem-n-Eye  uses reflectivity to indirectly impute Refractive Index, any variability in the  surface of a gem can result in some variance in your readings.  On the  whole, your  gemstone measurements should be within about +/- .010 of an RI value.

    It should be mentioned, however, that the Gem-n-Eye is much more accurate and  precise than similar instruments such as the Jeweler's Eye, Presidium  Reflectivity Meter, and Refractive Index Meter.  And unlike similar devices such as the Jemeter 90 or  the Gemmeter, the Gem-n-Eye properly accounts for Dispersion associated with  many high index stones.  For example,  while Strontium Titanate and Diamond share the same RI value of about 2.41, the  Gem-n-Eye nevertheless easily distinguishes between the two stones.

    The Gem-n-Eye is designed to be calibration free, that is, the factory calibration, combined with a  sophisticated temperature adjustment feature, keeps readings  consistent.  For users who want to fine tune measurements, the  Gem-n-Eye incorporates effortless, push-button calibration adjustment.

    Can the Gem-n-Eye distinguish between Natural vs. Synthetic gems of the same  species?

    No, but the same can be said for most gem ID tools.  As an example, a  lab grown Ruby has the same Refractive Index and Reflective properties as a Ruby  mined from the earth, so the Gem-n-Eye will still confirm the identity of a  Synthetic Ruby as a Ruby.  However, the Gem-n-Eye can certainly make  distinctions between valuable gems and their cheap imitations and simulants that  are of a different species.  This is the first order of business in Gem ID.

    How large is the Gem-n-Eye database?

    The Gem-n-Eye  incorporates an internal retrievable database of over 200 gems, with  complete property data on each gem.  However, by default, the instrument  works with just the 25 most Common gems that most of us are likely to have or acquire.   But the simple push of  a button expands that list to include Less  Common gems, and with another button push, adds Rare gems to the mix,  and with a final button push, includes Collector gems as well.  So from the amateur to the professional gem collector, the  Gem-n-Eye is easily customizable to your needs.

    What else does the Gem-n-Eye do?

    • Measures Specific Gravity of Calibrated Gemstones of known Weight
    • Integrates Color selection on ID lookup

    Since it has a built-in database, the Gem-n-Eye can  also serve as your main Gemstone Reference source.  For instance, suppose you discover a gemstone with an unusual name like Shanseres.  Just scroll  through the alphabetically ordered database of  Primary and Related Names to learn that Shanseres is a variety of Diopside.  Or  do a Quick Search for all Pink colored stones, and so on.

    Independent of its function as a Refractometer, the Gem-n-Eye also serves as  a  portable, handheld Gemstone Computer designed for a Combination Search of the database, prompting you for entries of any or all  of the following properties:


    bullet Refractive Index
    bullet Birefringence
    bullet Dispersion
    bullet Specific Gravity
    bullet Hardness
    bullet Conductivity
    bullet Color
    bullet Crystal System
    bullet Group

    In this capacity, the Gem-n-Eye shows its intelligence.  For  example, you can specify a percentage allowance of your measurements of the  quantitative properties like Specific Gravity.  Also, you can choose up to  two colors to match because if you're like some of us, you can't tell if a  certain stone is green or blue.  These "smart search" features will  prevent you from inadvertently eliminating a qualified gemstone species from  consideration in your effort to identify it.

    How portable is the Gem-n-Eye?

    The Gem-n-Eye can be used at your desk, but it is also  small and compact enough to take on a buying trip to a gem show, a flea market,  or foreign country.   Dimensions are 7.5" long x 4.1" wide by 2.3" tall.  It runs on either a  single 9V battery or a 115V A/C adapter, both of which are included.  A  padded carrying case with belt loop is also provided.

    What else comes with the instrument?


    bullet Light Shields for Loose Stones and Rings
    bullet Tweezers
    bullet Polishing Cloth
    bullet Set of 2 Reference Gemstones
    bullet Instruction Manual
    bullet Laminated Chart of Gem Variety Names
    bullet One Year Warranty
    bullet 30 day  money-back guarantee*
    bullet Made in the USA

    Please read the Buyer's Guide, and review the comparative table farther  below.

    How do I purchase the Gem-n-Eye?

    Just Add to Shopping Cart.  This product typically ships within 1  business day.

    Buyer's Guide: The Gem-n-Eye III should be considered by those who have  difficulty reading a traditional Critical Angle Refractometer, and/or want to  avoid the latter instrument's somewhat toxic fluid, and for those who work with  high index stones, including some Garnets, Zircon, and Diamond, etc.  But while  the Critical Angle Refractometer is a "determinative" tool because of its high  level of accuracy and consistency, and that it also measures Birefringence, the  Gem-n-Eye III should be considered more of a "confirmative" tool.  


    Features Gem-n-Eye III Digital Refractometer Traditional, Critical Angle Refractometer
    Principle Reflectivity (to indirectly impute Refractive     Index) Refraction (directly)
    Maximum RI 3.300 1.810
    Fluid requirement None Yes - some toxicity
    Readout Digital Readout on LCD Display Manual reading of scale
    Measure Birefringence No Yes
    Cabochon Measurement Only if bottom is flat and highly polished Spot Method on some models by advanced users
    Mounted Stones? Many - platform has recess for setting Only if table facet protrudes above setting
    Internal Database 200+ Gemstones None
    Other Features Gem ID computer with integrated Color and     Specific Gravity search None
    Calibration User Adjustable Fixed



    Features Gem-n-Eye III Digital Refractometer Traditional, Critical Angle Refractometer
    Readability Very easy Difficult for some users
    Accuracy of RI +/-.010 +/- .001 potentially
    Repeatability and Consistency Fair to Good Excellent
    Foolproof? No - gem must be clean and polished, and optical eye free of debris Mostly
    Gem ID Effectiveness Confirmative Determinative


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