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Best gem refractometer

Last Updated: 27.11.22


Gem refractometers – Buying guide & Comparison


If you don’t have the time to go through all the extensive documentation in the field of gemology and are just after a quick suggestion for a good gem refractometer to get you started then the following short paragraph should provide all the information you need. The gemkit3+book package was very well received by both beginner and experienced gemologists alike since it contains the most important tools to practice this hobby all gathered together in a convenient and surprisingly affordable package. The piece de resistance is the refractometer itself, certified to take readings from a 1,30 to 1,81 refraction index. Beginners will love this as a starter kit and experts will find it of great use as a portable, unpretentious unit. If you already have most of the items in the gemkit+ and only need the device itself and some RI fluid, then the Ade Advanced Optics ExtGemRefra will make for a good purchase.



Comparison table


The Good
The Bad



Whether you’re out to buy the best gem refractometer available for sale to equip your geology lab or just a hobbyist or corner store jeweler, there are a few things you to know about the product before making your purchase. We’ve looked through the best gem refractometer reviews online to see what are the most common attributes amateurs and professionals alike take into account when making an evaluation and listed them below.

First, the basics

The refractometer is one of the most important gem testing instruments since it lets you know two very useful parameters for gem identification: the refraction index (RI) and the strength of the gem’s double refraction (birefringence).

The refraction index is usually different for every gem and makes for a pretty straightforward identification method. Only some gems have a double refraction, and by taking two measures from such a gem you can calculate the strength of its birefringence, which offers further data for identification. Of course, the fact that you can separate mono-refracting from bi-refracting gems is very useful as well.

Like any refractometer, the variety used in gemology works by focusing the refracted light from the sample into a scale. The readings are then taken by viewing the scale through a focusing lens. Unlike with portable types, the gem refractometer will need its own light source to function, most commonly a monochromatic LED light on recent models. This gives it a great advantage over a microscope because it allows it to take readings of opaque gems as well as transparent ones.



This is especially important for scientists and jewelers since a good deal of their respective jobs involve taking accurate readings. The best gemological refractometers used in labs generally have a far lower margin for error than it might be reasonably needed by a hobbyist using his or her library books for reference.

Enthusiasts and even most jewelers might want to favor other characteristics over this one, such as how durable, affordable and easy to carry the unit is, since the most common margins of error specified by manufacturers are generally well within the parameters required for them to do their work.

To ensure for the most accurate reading, it’s sometimes required to compensate for room temperature. Certain units do this automatically, which makes for great convenience since the user won’t have to consult various charts and then make the necessary adjustments by hand.


Intended use

Before buying you should always consider what your needs from the meter are. Hobbyists and gemology beginner won’t need the highest specs model, and even specialists don’t feel too comfortable carrying their best refractometer on location.

Even more “affordable” refractometers can cost a pretty penny, but high-performance ones will really burn a hole in your pocket, so don’t get obsessive over specs when you aren’t in a position to benefit from them anyway.

Speaking of value for the dollar, make sure that you buy a sturdy, durable model, with a casing made out of metal rather than plastic.  



In order for the refractometer to work properly, the gem must be placed over a layer of refracting oil, which needs to be rated for the maximum refraction index that the device measure (generally 1,81). Make sure that the manufacturer provides an adequate quantity of fluid with the meter, so you will be able to use it straight out of the box for testing.

A bag for easy carry will be especially important if you plan on using the refractometer on the go. The need for transport in the gemology world arises more often than most of us would expect, so a good bag might well prove its worth.  

All models that come with an integrated light will also require batteries, and it’s always nice to have these included as well.



5 Best Gem Refractometers (Reviews) in 2022



1. Chelsea Filter Dichroscope Jewelers Loupe Refractometer


Containing a Chelsea filter, a dichroscope, a triplet jeweler’s loupe with 10x magnification and a gemological refractometer, this kit has everything to get a regular Joe started in gemology or to provide a highly convenient traveling kit for an expert in the field since it all fits in a discreet black case.

The meter can take accurate measurements of the refraction index between 1 and 1.80 units, enough for any task you might need it for. It also comes with its own LED light and batteries as well as 10 grams of RI 1,80 contact fluid.

The lenses are protected by a strong metal case while in use, and a nylon zip-lock back is provided for easy carriage.  

The whole package received good ratings on retail sites for its quality but what impressed people the most was the very good value they received for a price slightly above that of a mid-range refractometer.



This kit is great for beginners wanting to amplify their passion for gemmology due to the fact that it’s neatly packed in a black case which is very easy to take along anywhere you travel.

This item contains a Chelsea filter, a dichroscope, a triple jeweler’s loupe,  and a gemological refractometer, basically the whole package for the regular Joe just starting out in gemmology.

The magnification loupe included here has a zoom power of 10X, allowing you to closely examine any jewelry or gems you might be working with or studying from up close.

The meter is able to take accurate measurements of the refraction index between 1 and 1.80 units, making it good enough for any task you might need it for.



Some buyers disliked the fact that the tube with the contact fluid which comes with the kit did not look completely filled.

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2. External Monochromatic Yellow Light Gem Refractometer


The Nevada based Ade Advanced Optics seems to really have hit upon a gem with this product. It is both accurate, sturdy and contains some features not usually found in refractometers of its category.

The most salient of these is its automatic temperature compensation capability, which allows it to adjust for any climate within its operational range without the need for user input. This is especially convenient for gem hunters that need to carry a measuring tool to outdoors marketplaces or residential homes, where precise air temperature might sometimes be hard to determine.

The item is also easy to carry around, thanks to its low weight of just 0,8-0,9 lb and soft carry case. You won’t have to worry that much about dropping it since its thick glass optics and metal casing gives it good impact resistance.

The product also comes with its own RI oil rated at 1.80, a polarizing filter and a yellow monochromatic light, which would be difficult to find for sale otherwise.  



The convenience offered by this refractometer is quite outstanding, this being the reason why it is currently so popular among consumers.

This product is able to adjust to temperature changes in the environment, making sure the results of your measurements are not influenced in any way, shape, or form. This is a great advantage for gem hunters that need to carry a measuring tool to outdoorsy locations.

The manufacturer tried to make this as lightweight as possible so it’s an easy item to carry around, especially since you get a soft case which is provided with your purchase.

This is a very good product for the price asked since it is equipped with sophisticated features which may have allowed the company to charge some extra dollars for it.



The built-in light was not something enjoyed by every buyer out there, so potential customers should keep this in mind before making a decision.

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3. Ade Advanced Optics GL500 Gemological Refractometer


The comparatively affordable GL500 is an even more portable unit than its premium cousin, the ExtGemRefra. While its functionality and features didn’t receive the same praise (but no complaints either) its light weight and sturdiness make it very suitable for a gemologist working out in the field and for gem hunters making their way from stand to stand through crowded marketplaces or conference halls.

Both these qualities are a result of its aluminum construction and built-in LED light, which eliminates the need for a flashlight or any other sort of outside illuminator that would otherwise be required to be carried separately.

The importance Ade Advanced Optics gave to portability when designing this product is further displayed by the available accessories they decided to include in the package: a polarizing filter and two different carrying cases, one soft and comfortable while the other one hard, to offer adequate protection from physical forces.  



This model is a dream for gem hunters as it is very portable and it allows them to carry it to any outdoor location they may have to visit. 

Some buyers also like the fact that this unit comes with its own incorporated LED light, saving them the trouble of having to carry an additional flashlight at all times during work.

The aluminum construction acts as a barrier against outside forces, making this product lightweight and durable at the same time, exactly what a scientist on-the-go seems to be needing.

Ade Advanced Optics also decided to leave a final touch on this by adding some special accessories like a polarizing filter and two different carrying cases, one soft and comfortable and one harder, offering adequate protection.



Potential buyers should be aware that the necessary contact fluid is not included in this purchase, so they would have to buy it.

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4. LED RI Oil Light Gemological Refractometer


An overall good quality product, the TTG-181 offers all the functionality needed for the gemology enthusiast and jeweler alike. Its accuracy is specified by the manufacturer to be at 0,01 RI, which makes it sensitive enough to categorize almost every gem on the planet.

The range is equally suitable, between 1,30 and 1,81, covering every reference value you might find in a gemology catalog.

It’s got an integrated LED illuminator with an easy to access on and off switch and a polarizing filter, but you’ll need to shop for a bottle of 1,81 rated RI fluid since this doesn’t come in the package.

Portability is also good, with the item weighing in at only 0,88 lb and having its own carrying pouch. An instruction manual is also supplied by the manufacturer but the button cell batteries it requires to run are not.  



The TTG-181 is an overall good and durable product which offers all the functionality needed for a gemmology enthusiast and a professional jeweler alike.

The manufacturer deems its accuracy to be at 0.01 RI, which basically makes this device sensitive enough to categorize almost any gem on Earth.

The range was also something the manufacturer took into consideration, as it is equally suitable between 1.30 and 1.81. These numbers are good enough to cover every reference value that may be encountered in a gemology catalog.

The model also has an integrated LED illuminator, saving you the trouble of having to carry another flashlight. The illuminator has an easy-to-access on and off switch as well as a polarizing filter.



Any would-be customers need to keep in mind that they will have to buy their own bottle of 1.81 rated RI fluid since it is not included in the package.

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5. Losco Instrument Gemological Refractometer Build-in Light 


With an accuracy of 0,01 RI between the ranges of 1,30 and 1,81 RI this Losco Instrument product will make a good work aid for any scientist, jeweler and gemology enthusiast. Furthermore, it offers a similar degree of functionality as any other gem refractometer while not affecting your personal budget quite to the same degree.

Its affordability doesn’t take away from convenience either since you’ll go through the same usual motions while using it: Open the upper cover and wash the prism with alcohol.

Place just a drop of refracting oil and even it smoothly, so that the gem makes good contact with the glass. (the gem should be, of course, polished and smoothened out on its contact surface). Turn on the integrated light and adjust the focus on the eyepiece until the light/dark boundary appears clear on the scale. Mind that you



This model boasts an impressive accuracy of 0.01 RI between the ranges of 1.30 and 1.82 RI, making this Losco instrument a great catch for any scientist, jeweler, and certainly for any gemmology enthusiast out there.

Another bonus of this device is the fact that it offers a quite similar degree of functionality as any other gem refractometer out there while not blowing a hole in your 3-month budget. 

This affordability factor does not take away from the quality though since you will have to go through the same normal motions of opening the upper cover and washing the prism with alcohol.

Buyers also expressed satisfaction with the short amount of time it took for this product to be delivered to them.



Some customers pointed out that while this product does great on cut stones, it does not do so well on uncut ones.

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Ioana Moldovan

Ioana’s professional experience in the optics field has helped her understand the value of passing her knowledge forward. Her curious personality helps her gather useful information for her readers and her goal is to make technical information fun and accessible to everyone.

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3 years ago

I need refractrometer for gemological stones identification

James Greene
3 years ago
Reply to  Ch.RATNAKAR

Hi there. Please check our product list to see which one best suits your needs.

2 years ago

Hello. I trained in the U.K. on a gem refractometer with an external dial reader but I’m struggling to find one to purchase. Can you help? Thanks

James Greene
2 years ago
Reply to  Lucy

Hi Lucy. I’ll surely try to! Do you know the company that produced it? Protection Status