Faceting 101

Something a little different this month. Since there is not much mining to be done during these winter months I thought I might try and answer some questions regarding how a stone is cut. A lot of people have a mental image of a cutter taking a hammer and chisel to a stone and continually knocking off small pieces of material until he has a completed gemstone. In reality the process is basically one of grinding and sanding precisely placed flats or "facets" on a stone. Just like working with wood or metal progressively finer cutting material is used until the stone reaches the stage that it can be polished. So, have you ever wondered how a stone goes from a piece of rough material to a finished gemstone? Probably not but in case you have here is the "Steve's Stones Condensed Version" of the process. We'll start with a rough piece of tourmaline and follow it through some of the basic steps in the cutting process. Perhaps you will discover that faceting fascinates you also.

Faceting Machine Basics

Here is the condensed version of what makes up a faceting machine. Basically it consists of a rotating surface that spins upon which a cutting disc or lap is placed. It operates much like a phonograph turntable.

The other main part is the mast and faceting head. These parts allow the stone to be raised or lowered in height and changed in angle in relation to the cutting surface of the lap. The faceting head also has the ability to rotate 360 degrees in set increments to allow for accurate repeatability of facet placement.

"In the begining"...

Every process has a starting point. For facting the initial first step after examination of the rough is to grind a small flat where the table of the stone will be. This is where the "dop" which is a brass rod that is used to hold the stone will be attached. These two pictures show the top or "crown" of the stone with a flat ground on it and the uncut portion of the stone which will become the bottom or "pavillion" of the stone.

Here we go!

Here is the freshly dopped stone at the start of the cutting process. I grind a small flat to the stone and then attach it to the dop with super glue. The super glue bond is then coated with nail polish to waterproof the glued joint. It's a "bad thing" to have a stone come off the dop part way through the cutting process.

Cutting the pavillion

Here are a few pictures that show the process of cutting the pavillion (bottom) of the stone. Each facet is cut with at least two different coarseness of cutting lap, sometimes three. A intial cutting is done to rough in the shape of the stone. Then each facet is smoothed out with a finer grit lap and then finally each facet is brought to a prepolish stage. This is the fun part of cutting for me. Watching the transformation of the stone as I go from prepolish to polish is a sight to see.

Completed Pavillion

Here is the completed pavillion. All the facets have been cut in thorugh rough grind and prepolish. Then each facet has been polished. Halfway done!

Transfering to cut the crown

Once the pavillion (bottom) of the stone is cut it must be reoriented so the crown (top) of the stone can be cut. This is accomplished by means of a transfer jig and a high tempature wax. Once the wax has melted the two dop sticks are pushed together. Then, after the wax has hardened one of the dops is removed and you can begin cutting the crown. Pictured here is the finished pavillion on one dop being prepared to transfer to the second dop. The other picture shows the stone after the transfer has been completed.

Cutting the crown

These next two pictures show part of the process of cutting the crown facets. You can see the progression somewhat and how the different facets intersect each other.

Ready for prepolish

Here the stone is shown with all the facets cut in. The nest step is to recut the same facets with a finer grit lap. Then polish the facets and we are done!

Almost done.

Here is the almost completed gem. All that remains is to heat the dop up to melt the wax and free the stone. Then a short soak in rubbing alcohol to remove the rest of the wax and be wiped clean. At this point the stone is weighed for finished carat weight, priced and readied for sale. The creative talents of a jeweler/metalsmith will take over at this point. Who knows, perhaps a one of a kind ring or pendant or maybe simply to reside in the collection of a connoisseur of fine gem stones.

Finished Stone

Here is the end result of my work. A fine gem tourmaline that weighs in at 3.6 carats and measures 11 x 9 mm. This stone is all ready for the new owner to have a custom piece of jewelery designed around it. The possibilities are endless and only limited by the skill of the metalsmith and the budget of the customer!! At the very least we now have a fine gem that will put to shame most mass produced production items.

ROCK ON!

Steve