 Setting
Larger Gemstones
Setting larger gemstones in four prong type settings is
significantly more difficult than setting smaller stones. Beginners
should not attempt this until they are very comfortable in setting 8mm
stones in similar four prong type settings. There are many reasons
why the larger stones are more difficult, one of the easiest to understand
is that the metal used to make the larger setting is also larger and
therefore more difficult to bend. Another reason is that the
manufacturers that make these larger settings aren't making them for
beginners, they are made for professional jewelers. This doesn't
mean that advanced beginners to setting gemstones can't perfect this
skill. It just means that
 you
have more things to consider and to learn when setting larger gemstones.
The first steps in a project like this are to select your
materials. We are using 12 mm round, brilliant cut gemstones and a
four prong pendant setting as shown at right. The important thing
for a relative newcomer to setting gemstones is to purchase a
 "notched"
setting. In the picture at left, you can view the notches in three
of the four prongs in this setting. These notches are cast as part
of
this setting and when received they may contain some casing residue.
It is a good idea to use a jeweler's file and clean out the notches by
filing each one in turn with either a triangular file or with the edge of
a flat file. The notch has to be big enough to accept the "girdle"
of the gemstone. The girdle of the gemstone is the widest part of
the stone as shown at right.
The second consideration in selecting your materials is to
avoid gemstones with a wide or fat girdle. The girdle should be no
wider than 1mm and preferably not that wide. Any gemstone with a
girdle that is wider than 1mm is not a good candidate for setting by
anyone but a professional.
When you have your gemstone and setting ready, position
the gemstone with
the table flat on your work surface and position the setting upside down
on the work surface as shown at left. Now you need to test
whether the setting is properly shaped to hold the gemstone. Lift
the setting and position it over the gemstone gently. Do not push
down yet, just lightly position the stone. When the setting is ready
for your gemstone, the prongs of the setting will be about .5mm smaller
than the gemstone itself. (So far, with larger settings, we have not
found any setting that was ready right out of the package.) You want the
prongs so that they setting will require some pressure to snap into place.
That way the stone will be held firmly by the setting. In most cases
with larger gemstones, the setting will accommodate a gemstone that is
about 1mm larger than the size indicated.
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