Faceting as a Hobby
By Jack Christianson
MWF Award Winning Article Courtesy THE ROCKTABLET
Newsletter of the Neville Public Museum Geology Club, Green Bay, Wisconsin

What is a hobby anyway? Quoting Aldo Leopold: "Becoming serious is a grievous fault of hobbyists. No hobby should either seek or need rational justification. To find reasons why it is useful lowers it at once to the ignominious category of any 'exercise.' A hobby is a defiance of the contemporary. Every hobbyist is inherently a radical, and his tribe inherently a minority." That being said, let's see why this faceting can become an addiction and what is involved.

First, people come to the faceting hobby by many routes. Some are introduced via the cab cutting route. Some are the result of seeing it done at a rock show. Some are taught by friends. Some large clubs have machines and instructors. Some become interested by reading about it and are self taught. For others it is an outgrowth of an interest in mineralogy. In this area, classes are available at the technical college.

The idea of taking a rough, transparent pebble and turning it into a flashing thing of beauty is quite appealing to most people. It's intriguing to do this to a substance that may have taken untold millennia to form.

One can always find reasons not to facet. Age, lack of perfect eyesight, or less than very steady hands are not valid reasons. And once you get started, oh boy, trying one cut after another is just like eating popcorn, you just don't want to stop.

How many of these gems does a hobby faceter cut and just what does he or she do with them? The number depends on if you are in a class and limited to one night a week or have your own machine at home. One night a week may limit your output but the fellowship certainly is more rewarding than just sheer volume. If you own a machine but are somewhat less gang ho, let's say you cut one stone a month. At the end of five years you would have sixty gems. Neat, eh?

Some folks like making a collection. Others enjoy the ohs and ahs that cutting brings. How about a pretty pendant for your wife or a tie tack for your boyfriend. One large blue faceted stone traveled the Midwest with my wife as the focal point for inspirational talks to Christian Women's Clubs. Museums are often interested in donation of gemstones.

Other facets of the hobby: There's a lot of fun in trading of ideas and techniques with those of greater or lesser expertise. A much greater appreciation develops for what others, professional and otherwise, have done.

One learns to laugh at mistakes and learn from them along with fellow students, all of whom have also erred. Perhaps as experience increases the idea of competition will have an appeal. This is a great way to fine tune ones cutting and have the efforts critiqued by experts. There are guilds that have monthly educational publications available. A monthly booklet is sent out to members of the American Society of Gemcutters. Computer programs are even available to enable a gem to be cut on a screen before trying it on an actual stone.

Cut What

Almost any transparent material is a candidate to be faceted. The most common, plentiful, and inexpensive is quartz. As a result most people cut their first gems in clear quartz.

Quartz is a simple oxide of silicon, the two most common elements in the earth's crust. A chemically pure crystal is colorless. The refractive index is high enough to make a brilliant stone and it is hard enough to permit its use in jewelry for daily wear. To perfect the cutting of quartz as a first step in learning to facet is smart for many reasons. Being hard, it won't cut away too rapidly. It usually takes a good polish without too much trouble. It has no cleavage plane to worry about. It cuts at almost the same speed in any direction. Mistakes, which all of us make, in an economical material are less damaging to our purses than to our egos.

Another reason for learning to cut quartz first, is that many of the future gems you cut of various colors will still be your old friend the quartz. Smoky quartz is fairly inexpensive and, depending on the depth of color and hue, is a fine topaz look alike. Citrine is a yellow to reddish color and comes in all shades in between. Rose quartz is pink and is sometimes clear enough to cut a splendid gem. Amethyst, the most recognized of the quartz family gems, varies from a pale lilac to a deep royal purple. Very pretty gems are also faceted from rutilated quartz.

One might think that such a low cost material would not provide many with any incentive to duplicate what nature has done so well. Not so. Man-made quartz has been available for a long time and now is being produced in amethyst color.

Faceting Synthetic Materials

Before discussing a few of the scores of natural materials available, we should take note of some of the synthetic ones.

Glass of various kinds has been made for centuries and faceted. It comes in almost any color and by various names such as synthagem, victoria stone, laser blue, lead glass, etc. It's easy and fast to work with and can be very pretty. They are a bit too soft for ring stones and better suited for use in pendants. These are great for experimenting.

Some of the harder materials, which usually have a higher index of refraction, have been used as diamond simulants. These include YAG, GGG, CZ, rutile and spinel. These all have different dispersion, the ability to break up white light, and many are the result of laser research.

Synthetic corundum, ('ruby' or 'sapphire', depending on the color) is the hardest of the synthetic materials and comparatively economical. It is even made in a color change type. Synthetic emerald, (dark green synthetic beryl) is one of the most expensive of the synthetic materials and works very much like quartz.

Faceting Natural Materials

When deciding to purchase a natural material for faceting we have a number of things to consider. Cost aside, at the top of the list is color. This is somewhat subjective as our tastes differ. However, the intensity of comparative brightness, as well as the depth of color is important. The choice may be dictated by whether the stone is primarily to be cut for the color or the brilliance. If brilliance is the object, then the clarity and lack of flaws is most important. This and the depth of color are determining factors in what the price of both rough materials and finished gems will be. Rough amethyst, for example, can cost anywhere from 10 cents to eight dollars per carat.

Next, one must choose a material with the physical and optical properties that are compatible with our equipment, experience, and the intended use of the gem.

We are very interested in hardness. There is no point in cutting a beautiful cherry opal, which is quite soft, to get set in a ring for daily wear. Soft stones may be difficult to set in jewelry and usually require special attention to polish. If handled carefully, they are fine for pins, pendants, earrings, or display.

The refractive index is important in how brilliant a gem will be. I have graphed a nonlinear correlation between the hardness and high refractive index of gemstones that is useful only as a general rule.

Other properties have to do with the handling and cutting. If a material is heat sensitive, it must be cold dopped or have its temperature changed very slowly. The cleavage planes in materials like topaz and kunzite have to be taken into account. They affect the orientation as well as the cutting and polishing procedures that can be used. Crystal twinning and brittleness also should be considered.

Size versus weight! A little simple math. A two carat stone is only 26% greater in diameter than a one carat stone and has 60% more viewing surface. If you want to cut a stone twice as large in diameter, you have tour times the viewing surface and eight times the weight.

The cost of rough natural material is exponentially higher per carat as the weight increases. Thus, a piece eight times as large will probably cost 64 times as much. Just to put this all in perspective, recovery is usually in the 20% neighborhood, meaning that it takes a five carat piece of rough to cut a one carat gem. Man-made material, on the other hand, generally has a per carat price that remains constant in spite of size. Doubling the diameter then only costs eight times as much.

Where and how to obtain material? Lapidary shows, rock shops, mail order, swapping and digging your own. The best way is probably by mail order on approval. You can then test the pieces you like and view them in a refractive fluid at your leisure and under the lighting conditions that you choose. This will help you identify flaws and color banding that you would probably not otherwise be able to see. You also have a better chance to determine if the shape of a piece will suit your needs. If preforms are available, they are easier to judge. Only occasionally is tumbled material such as peridot offered and this is quite easy to evaluate.

Don't overlook good material that is poorly cut as a fine source of supply. How about digging your own? I expect the cost per carat is about the same as the cost per pound of the fish I catch. The pleasure experienced should be about the same and the rocks keep better.


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Bob Keller