Initial Impressions of No Name Refractometers

When I opened the package, one difference was apparent immediately. The “no name” instrument was much smaller than my GIA Duplex II refractometer. (See the photo above for a comparison). The hemisphere, lens, and light opening were less than half the size of the GIA unit. I expected this would cause problems. However, once I started my tests this turned out not to be the case.

The Good

First, I tested a number of identified faceted gems with established refractive indices (RI). To my surprise, I found the “no name” unit much easier to use than the larger Duplex II. The smaller hemisphere creates a smaller viewing area. Thus, the stone is centered automatically in the magnifying lens.

Compared to the Duplex II, this was a delight. With it, I usually start with the magnifying lens off. I get my head in the proper position to view the shadow and then replace the lens. With the smaller refractometer, all this was unnecessary.

The Bad

Next, I tried doing some spot readings on cabochons. Here, the smaller and lower magnification lens really fell short. Getting an accurate spot reading from this little instrument proved…