How to Facet Gems

Unfortunately, mankind is never satisfied with a thing of beauty; he must improve on this beauty. He does so this with practically everything that the hand of man touches. This even includes the beautiful flowers of nature the clear crystals that make up gemstones. He does this by a faceting a set of new faces on the original crystal providing it is clear enough and shows all imperfections.

The faceting process is done with a specialized machine that is called a faceting machine. This is actually a grinding machine that uses diamonds as the abrasive. There is a hand piece to hold the stone to be polished onto a dop stick. The machine has a mast that allows a hand piece the freedom to move 360° around the mast. The hand piece itself is placed in a 90° quadrant that can be mechanically set at any angle the operator desires. The hand piece also includes a built-in indexing head so that the operator can index to love ever setting he desires.

A faceting machine itself is like a tank with the working parts inside the tank. This includes both the mast and a grinding wheel attached to one arbor that comes vertically up through the bottom of the tank. This arbor is attached by a belt to electric motor. This applies the power to do the grinding.

The dop stick is usually made in pairs, one that is flat on the end, and the other has an internal recess of about 60°. A pre-formed gemstone is attached to the dop stick having the internal recess. This is done using a hot wax very similar to sealing wax that is called dop wax. This wax comes in sticks that are about three quarters of an inch square at about 6 inches long. In use the end of the dop wax is melted and the flame of an alcohol lamp. A drop of this wax is applied to the end of the dop stick, and while it is still soft the pre-formed gemstone is inserted into the wax. This is then allowed to harden so that firmly grasps the gemstone. A special tool is then used on the mast to grind the table facet of the gem. This is a flat facet located at the top of the gem, and is the largest facet found on a gem.

Once the top of the gem has been ground flat it is then polished. This is done by replacing the grinding wheel with a lapping wheel. There are several different polishing compounds available but the most commonly used is cerium oxide. These are available as pre-charged sand plastic discs about 6 inches in diameter. Once the table facet has acquired a high polish so that it looks like a piece of glass the other so called crown facets are ready to be applied.

Although there are many different forms of faceted stones the most common one is called the perfect facet. This is a round stone with eight major facets, and eight smaller facets set halfway between the major facets. These are called to star facets, and reach down about a third of the way down the junctions of the main facets. There are an additional 16 facets that are made by changing your index head a quarter of a turn on either side of the main facet. Each of these facets are ground to a specific angle determined by the re-fraction angle of the gem. Once these facets have been ground they are then polished to completion.

Now we are ready to work on the pointed end of the gem that is called the pavilion. There are also 8 main facets on this side of the gem that are ground at the same setting as the eight main facets the crown side of the gem. There are an additional 16 facets that are ground at the same settings that the 16 facets were ground on the crown facets. These facets extend for about a third of the way down the junctions of the main pavilion facets.

The grinding wheels that you use are charged with different sized diamonds. For roughing out the stone you use a 125 mesh diamond wheel. For intermediate cutting it is normal to you use a 600 mesh diamond wheel. For finish grinding you use a 1200 mesh diamond wheel. There is a cast iron disk attached to the arbor that underlies the diamond wheels in use. After you have finished the grinding process the diamond wheels are all removed from the arbor just leaving the cast iron disk. It is on top of this disc that you place the polishing discs to finish your stone.

Another thing you should understand is that you have to transfer the stone when you have finished the crown facets to a flat in the dop stick that attaches directly to the table facet. This is done with a handy little device called a “V” block that clamps down on to both dop sticks so that you can make the transfer. The flat ended dop stick is prepared before you set it into the “V” block by attaching a dab of dop wax to its flat end. You then put the other dop stick into the block, and by shoving it forward so that the crown into the gemstone is pressed into the wax. The wax is then allowed to harden so that it has a firm grip on the gemstone. You very carefully take your alcohol lamp and gently heat up the other end of the gemstone. This will release it from the old dop stick. You can then remove this, and you are left with the gemstone attached to the other dop stick. This process works either way.

The diamond grinding wheels can be purchased, or you can make your own by charging a 6 inch disk of copper with the proper size of diamond paste. It is necessary to drive the diamonds into the surface of the copper disk this is easily accomplished by turning the machine on and using an old ball bearing held against the grinding wheel to set the diamonds.

It is also necessary to keep the gemstone cool while you are grinding and polishing. This is done for a can of water dripping down onto the grinding wheel. This not only keeps the stone cool but it also washes away what is ground off.

Now that you have finished your first gemstone, you may admire your handiwork, and cherish your thing of beauty.