Gemologists can't do an adequate job without tools that will aid in the identification and grading of a variety of gemstones. The list of the most basic tools is brief -- beginners will find reference books, websites, a loupe and a pair of tweezers to be sufficient to start. But if you’re delving more deeply into gemology, you'll want to invest in a good selection of tools. You may discover, as with most jobs, your task becomes easier when you have the right tools.
The ability to properly magnify a gemstone for study is essential for gemologists. A quality, 10-power loupe -- also known as a strainless sphere (a glass sphere containing no strain lines) -- should top your tool list. In addition, a good quality microscope is necessary to help you differentiate between natural and synthetic gems. You can purchase a portable microscope to take with you on gem-buying trips, or you can invest in a more expensive stationary binocular microscope with a zoom lens. A moderately priced scope may be just as useful for all-around work.
The Refractive Index, or RI, is used in identifying how light passes through a transparent material, such as a gem, and provides a measure of brilliance. A refractometer is the best tool for this determination, although a microscope will work to a lesser degree. New refractometers can be expensive, ranging from $500 on up at the time of publication. You may be able to find a used refractometer more economically online. You might prefer a Jemeter, also used for testing the refractive index of a stone. This unit is battery-operated and portable, ideal for working in the field.
Gemologists require a means of evaluating a stone's specific gravity. This is sometimes done using heavy liquids by observing how much a stone will float or sink when submerged in the liquid. This method is not as accurate as using a balance beam scale, with one pan of the scale submerged in water. These scales offer precise readings, as opposed to estimates using the heavy liquid method. Accurate balance beam scales are relatively inexpensive and can be found for less than $100.
Another useful tool is a dichroscope. This instrument enables you to view color separation in dichroic materials -- materials in which differently polarized rays of light are absorbed in varying amounts. This simple tool is small enough to be handheld and is comprised of a magnification source, plus two pieces of polarizing material situated at 90-degrees to each other. Some gemologists have made their own dichroscopes, although they are, for the most part, modestly priced.
A sufficient light source is a must for gemologists. Some tools come equipped with their own specialty lights, but it's advantageous to have additional illumination, such as a lamp. Choose one with a flexible directional arm. Incandescent and fluorescent lights will result in varying colors in some stones. The ideal lighting is incandescent or natural, such as filtered sunlight, which is considered the optimal way to make color comparisons. Daylight-equivalent lighting can be useful in some, but not all, cases so it’s best not to rely on it exclusively. Ultraviolet light is helpful in identifying certain stones, although not necessary. If using ultraviolet lighting, you’ll want both long-wave and shortwave. A Chelsea filter can come in handy for differentiating similar gems with different color value structures.
Having useful reference books for gem comparison and identification should really be No. 1 the list of necessary gemologists’ tools. The International Gem Society makes note of several: “Color Encyclopedia of Gems,” by Dr. Joel Arem, is considered “the most complete book written” on the subject, although it is currently out of print used copies can be found; “Gemstones of the World,” by Walter Schumann; and the “Gem Reference Guide” and the “Handbook of Gem Identification,” both available from the Gemological Institute of America.
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