I've been called upon many times to explain & demonstrate on how to prepare & set Princess, square-cut stones. On a Difficulty Scale on this style of setting is a very definite 25<>30 out of 10. This style of setting is not for the timid, or beginner! The tool & bur selection is as follows. Triangular-shaped 20, cm's in length file & number #4 cut, Pillar-shaped file number #2, the required burs are very basic in the selection of round bur #008 & bud-shaped bur of #007. Including a Polishing paper of #800 or even a #1,200 grit...(photographic-attachment is shown here).
The stone in this demonstration is a Cubic Zirconia with a "Swarovski" brand name & hardness rated at 8.5+ on the Moh's Scale, as these are quite resistant to breaking & no aggressive filing can damage any of the facets during the setting process.
In this essay, is a new ring that I modified to take a 6.5 mm square stone, why this size?
It is easy to view & fully understand every setting step in this somewhat difficult process. Upon examining the stone for any inclusions, I will hasten to add that any fractures or 'disturbing defects' must be immediately noted or you will be at fault!! This does & sometimes happen if this could be a "remounted stone".
At first glance, I will widen the distance between the 4, claws/prongs. I need full access to get my handpiece & burs to initiate any cutting of the bearings that on a horizontal angle. At now I will drill approximately 1/3 down from the claw tip, is where I will use my round bur #008. I will laterally drill into the 'vee' shaped claw, how far into the claw will I drill? It's until the whole round bur is in the metal!...(photographic-attachments showing this) This is just where the point of the stone will be laying, but never touching any metal. The four points are the "Achilles Heel" of the stone. When the two sides of the claw is resting against the girdle of the stone, no metal will have any opportunity in touching the 'point of the stone'.
From the juncture of the #008 round bur hole I will create two bearing-cuts, or "seats" as this is for the side-girdles of the stone...cut right out from the joining of the two sides, to the ends of each claw..(there are photograph-attachments showing this)
Before any stone is to be set, all of the "Gallery" metal must be cleaned & if possible polished.
If you wish to use the "Magnetic-Tumble" the ring, please do so now! This cleaning process is so important, no other time in setting of this stone, can the inside of the ring be made ready for the setting. Make very sure all of the 'bearings' are correctly contoured & carved. Once the stone is in the ring, it is safe to say the stone will find it's own place to sit. All of the girdle-sides or edges will be sitting correctly & inline with the points of the stone in relationship to the "Vee" shaped claws. I instruct my student to even use a Pumice Wheel & clean up all of the claws before the stone is set. Aggressive, Tripoly Cloth-Wheel Polishing could be used, but the downside is that the sharp edges of the claws might be made slightly rounded. I'd use the tumbler which is less prone to wearing down the edges of the claws.
Just prior to the setting of the stone, again make sure that there are no inclusions anywhere in the stone. Examine the 'resting place' for the Pavilion, or the underneath section of the stone.
Use your Loupe & quality-control every millimeter of the claw/prongs. For the first time place your stone in into the 4 claws/prongs & then again examine how the stone is sitting & the girdle must be at 90-angle to the axis of the ring..So important, there are no shortcuts ever allowed !!
The most important step is now to follow, "closing up the "Vee"-shaped corners". there is only one way to do this. DO NOT CLOSE (the claws) POINT-TO-POINT!! But here is the best way and my hand-drawn diagram will assist you. Inside of the "Chevron claw" is that #008 bur hole.
DO NOT LET ANY POINT OF THE STONE TOUCH ANY OF THE INSIDE METAL! You are now closing up all eight-sides (8) of the claws, not the 4 holding sections of the stone. In this process, you should be using a fine-toothed pair of pliers! I engrave lines into the tapered point of the jaws of the pliers with a "Corundum, Separating Disk". This allows the pliers not to slip off while bringing in the "Chevron" claws! This can be very disastrous if anything happens. (shown in the photograph & diagrams). Prior to filing of the claws, I will if space permitting, I will use my Flat graver #40 & cut inside of the "Vee shaped" claws just to give the inside edge a thinner appearance.
When starting to finish the filing or trimming of the claws, as my own teacher & instructor then suggested, is to carry down from the stone-facet, to the outside edge of the claw
(shown in the photograph), then they will have the same angle to the claws..You will notice that the claws are getting "more blended to the stone"..no longer will they be set with a hunking boulders of metal. they will be almost invisible. (shown in a photograph) All of these steps are done with your Triangular #4 cut file.This is a skill all unto it's own!
This essay on setting a Princess stone & their techniques is one of the most difficult to write about, so many rules & scheduling of events. Remember, no short-cuts are permitted!!!