for the Lab and in the Field | |
 One of my students at work with the spectroscope. Photo: E. Skalwold |
Here one of my students is shown using the large OPL Teaching Spectroscope mounted in its stand. She is adjusting the angle of the fiberoptic light for optimal internally reflected light in a flame fusion synthetic ruby cabochon which sits on the rotating stage. Near at hand are the spectrums of ruby and almandine garnet for reference - these are the two which she has narrowed the separation down to, discarding other red gem spectrums such as zircon, selenium glass, "ruby" glass (Au), REE red glass (rare earth 580 doublet), pyrope garnet, spessartite garnet and spinel. |
Arguably - because some will argue with good reason (my personal first choice is a microscope when available) - along with the loupe, spectroscope and dichroscope, the refractometer is probably the most important piece of equipment in the gemological toolbox. There are many models and types which all work on the same principal, that of total internal reflection (TIR). They are all expensive, fragile, somewhat bulky (except for the Duplex III) and require hazardous RI liquids to use. Refractometer Comparison |
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 Student lab-bench showing many of the essential tools of the field of gemology. Photo: E. Skalwold | |
Portable Gemological Equipment | |
 Surrounded |
In a hectic gem market where the heat is over 100, the activity is intense and the pace fast, the tools at hand are a 10x loupe, a good pair of tweezers and a selection of flashlights.... one does the very best one can with what is available. |
Far away are the sorts of instruments found on the lab bench - heavy, bulky or just not suited for travel. But, there are some wonderful portable or improvised tools which, if the need arises, can be easily brought along or drafted from the condiment tray of that day's lunch (be sure to clean out the fish sauce first). There are several sources of fine gemological equipment. There are even many instruments you can economically construct on your own, especially if you familiarize yourself with the techniques developed by Alan Hodgkinson and Dr. William Hanneman. |
 Sauce dish works for immersion in a pinch. Photo: E. Skalwold |
I am a tool junky - here are some favorite choices.  | |
 GemPro Portapac Photo: Jeff Wildman. |
As an apprentice to a senior gemologist, now retired, I was introduced to the line of gem testing instruments supplied by Jeff Wildman, inventor of the PortaLab. His company, Gemological Products, carries many essential tools and really shines with its line of portable equipment, including the Portapac (pictured at left), GemPro refractometer (below) and the infinately useful Mega-loupe. GemPro Refractometer Photo: Jeff Wildman. |
| An excellent article entitled "Portable Instruments and Tips on Practical Gemology in the Field" is to be found in GIA's journal, Gems and Gemology Vol. XXXVIII, Spring 2002 (back issue available on the GIA website). This article gives very favorable reviews of Gemological Product's PortaPac and Portalab as well as reviews of other instruments favored by the author, Edward W. Boehm. | |