A. Examine the Emerald's Surface
the entire surface of the stone is covered with small pits. While
the pits aren't visible to the naked eye, they do effect on the brilliance
of the gem. The reduction of brilliance may not be readily apparent,
as it requires experience gained through comparing various gems.
you may have trouble distinguishing if the marks are on the surface
of the gem, or inside the gemstone. To solve this, rotate the gem
so the light reflects off the facets. When a facet acts as a mirror,
inclusions beneath it disappear, but scratches on the surface are
should be polished. If not, it indicates that the gem was cut in a
hurry. A custom gem cutter would finish this off. Diamonds are cut
different than colored stones because of their extreme hardness. A
rounded and unpolished girdle is common on diamonds.
are the facet edges? This is an interesting clue to look for. Diamonds,
with their incredible hardness, have the sharpest edges. That is a
clue to their identity. Harder colored stones, such as: CZ's, rubies
and sapphires come in a close second. Softer gems, those below nine
in hardness, will usually have slightly rounded facet edges. Once
in a while you will come across a custom cut gem with exceptionally
sharp edges in a material that is only 7 or 8 in hardness. Even though
you may not be able to appreciate all the subtle decisions that went
into cutting a gem like this, you can spot the quality of workmanship
by the polish, meets, and facet edges.
gem upside down and look at the culet. It may be chipped. This is
called "paper damage" and can occur when gems are carried
together in paper wrappers. Again, if it isn't visible without magnification,
it won't have a significant effect on the beauty of the gem.
thing to look for is how even the contour is. A cabochon should have
an even curvature to its surface. Look at the cabochon from both ends
and both sides. The shape, or curvature, should be a mirror image
from side to side. No area should be thicker than its opposite and
there should be no bulging.
The second way to judge the shape is to hold the gem so light reflects off its surface. Then move the gem so the light travels across the top. If the surface is properly cut, you will see the band of reflected light glide evenly over its surface. The band of light will begin to snake if there are any irregularities. The very top of the gem is where you are most likely to see this. Often a small area will be somewhat flattened. This is hard to see when viewing from the side, but quite obvious as light passes over it. The fact that light doesn't flow smoothly over this area is why it is considered to be second-rate workmanship. However, if you look closely, that area probably doesn't have as good a polish either.