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Cut

The cut of a gemstone, the workmanship that went into fashioning it, is one of the most important factors in its appearance. It is also one of the most difficult factors for the non-professional to judge because of the number of variations involved.

The first thing to do is to look at the shape of the stone. Some gems are cut "free form" but most are intended to be a regular shape. If so, look at the symmetry. Does it bulge here or there, or is it symmetrical in all directions. Look at the stone from the side and the ends. Again, it should be symmetrical in all directions. If not, it is up to you to determine how much it will affect your appreciation of the stone.

When considering a gem, insist on inspecting it with magnification. Look at areas where light is being reflected from the surface. They should be smooth and mirror like. If you see pitting, scratches, or dull areas, the gem is not well polished. It may look good in the store, but someday you will compare it with a well-polished gem and be disappointed with your purchase. If it is a faceted gem, look at the facets junctions also. On a well-cut stone, they will be crisp and come together in a single point. You may see facets that are slightly rounded and not quite meeting where they should. Just how far off they will affect the brilliance of the gem.

The other factors in a faceted gem are too complex for the layperson. However, you can get a good idea of the cutting quality simply by comparing it with other gems. When you do this, make sure you are comparing similar stones. An amethyst will never have the brilliance of a topaz and dark stones will not be as bright as light colored ones. When comparing like stones, what you want to look for is the overall light return, the brilliance and sparkle of the gem. It is entirely possible to look at two gems with the same size and coloring, but one having much more brilliance and sparkle than the other. This is the result of cutting.

One thing to pay special attention to is "windowing." That is where light passes straight through the center, rather than being reflected back. It is easy to spot; the center will be much lighter than the outside of the gem and will have no flashes of light. Some windows are small; others are quite large and hideous. This is another example of something that might look good in the store, but someday you will compare it with a well-cut gem and be disappointed with your purchase.

Cabochons are easier to judge. We should begin by checking the polish under magnification. Then hold the stone at a short distance from your head and rotate it slowly. Notice how the light passes across the surface. On a well-cut gem, it will flow smoothly from one side to the other. If it is poorly shaped, the light will not flow smoothly, but snake across the surface. Surface irregularities and poorly polished areas will also show up this way.

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