I’ve been quite skeptical of the inexpensive Chinese-made refractometers often found on eBay for $100 or so. In my experience those units have been difficult to use and provide mediocre results. It’s one thing to use a poor to mediocre refractometer if you’re an expert with a lot of experience, but it’s another thing entirely to attempt to learn on a mediocre instrument. A good deal of frustration is likely to occur in the latter case.

The difference between a cheap refractometer and the lowest price high quality unit I recommend, Jeff Wildman’s GemPro unit, is the difference between $100 and $545. Dr. Bill Hanneman chastised me for not having something more modest in price to recommend, and so I set out to find a higher quality, reasonably-priced refractometer.

Philosophically, I am opposed to promoting blatant copies. The Eickhorst refractometer is the one most blatantly ripped off by the Chinese and in deference to the time and money my German friends have spent developing quality instruments I will not review the knock-offs.

I did manage to find an excellent Chinese-built unit sold by OpticFactory on eBay for $285.99. Their Model FGR-003 also has “Fable” printed on the hemicylinder cover. The FGR-003 comes very well packed in an aluminium carrying case. The unit has a built in LED-based yellow light source that is powered by two AA batteries or a small 110-240V power supply with 3VDC output. Unlike some similar units the light source is not anemic and is quite powerful enough to do the job.

The unit comes with a small bottle of RI fluid with a push-in contact applicator that seems like a good idea but is a bit difficult to control. The RI is only about 1.78. I much prefer 1.81 fluid for everyday use and I keep some 1.85 fluid from Cargille close-by although it is toxic and all the usual caveats apply.

The unit has a CZ hemicylinder that is quite a bit harder and more abrasive resistant than the typical Schott glass hemicylinder. Also included are a built-in telescoping focusable eyepiece with a detachable polaroid filter. The eyepiece is not detachable. The polaroid filter fits nicely and securely in the eye-piece and the chances of inadvertently knocking it off are minimal. For some reason I am constantly knocking the filters off my Duplex II and GemPro units, so I like this feature.

The unit is generally the size of most refractometers and measures 140 mm x 90 mm x 40 mm.

While the coefficient of dispersion of the CZ hemicylinder might be an issue with an externally lighted refractometer when attempting to take dispersion measurements of a gem, this is not possible with the single internal light source of the FGR-003 so the CZ hemicylinder is a significant overall asset to the design.

I found the scale very easy to read and the shadow lines very sharp making interpolation to .001 quite easy, better even than my Duplex II. The unit also came perfectly calibrated.

Although you have to give up the option of using different external light sources, that is the only compromise with the FGR-003 which is otherwise an excellent instrument at a quite reasonable price.