V Prong Setting
To V or not to V? That is the question. Whether ’tis nobler in the minds of thou customers to place upon their marquise a prong in the shape of a V, or dost thou leavest it exposed to the concerns of the world.
Ok, William Shakespeare I’m not. However, for the bench jeweler, the question remains. What do you do with this prong in the shape of a V?
Several shapes of stones have pointed ends, including marquise, pear, heart, and princess. Because these points are often thin and fragile, it is important to protect them with a prong. This is particularly important on rings where the stone may be subject to more abuse than in pendants, earrings, or brooches. Although a standard prong will usually suffice, a V shaped prong is preferable. A v prong provides additional protection and will more securely hold the point of the stone.
Special care is necessary when setting these stones to keep from chipping or breaking the point. Extensive preparation is necessary and work must be executed with precision to properly set them. Nothing short of true craftsmanship can be exercised while attempting to set a stone with pointed ends.
The seat in the v prong may be cut with a variety of burs, gravers, drill bits, or files. There is no one best method. The method used will depend on the situation and one’s own preference of tools. The following is the basic procedure I most often follow.
Using a small hart bur cut a line on the inside of the prong at the height you want the girdle of the stone. Check and double-check that this line is at the proper height and is straight and level. In addition to beginning to form the seat, this line will serve as a guide to base all future cutting on. If this line is off it will be near impossible to set the stone straight. This line does not have to be very deep at this point (it can be cut deeper later); however, do not cut into the prong more than 1/3 the thickness of the prong.
Next turn the bur 90 and cut a line down the center of the prong. This cut, along with the first cut, will form a cross-shaped pattern in the prong. This second cut will allow clearance for the pavilion of the stone. It is particularly important on the heavier cast v prongs.
Using a bud bur cut a hole in the center of the cross. Cut no further than ? the way into the prong. This hole creates the void surrounding the tip of the stone. Make certain there is a cavity below AND above the tip of the stone. Putting pressure on the tip of the stone from above with no support underneath will cause the point to break off.
Finally trim away any excess metal and smooth the seat using a polished flat graver.
How you cut the seat is not nearly as important as what you accomplish. The seat you cut in a v prong must accomplish three items:
- A smooth even seat which will support the sides of the point on the stone.
- A void to surround the very tip of the stone.
- Enough metal must be removed to safely push the top of the prong over the stone, while leaving enough metal to securely hold and protect the stone.
Once the seat is cut completely, examine it for these items with a loupe or microscope. First examine the seat, then lay the stone in the setting and re-examine it. One small bur of metal or ripple in the seat is all it takes to break the point off a stone.
ALWAYS check the stone with a loupe or microscope before you begin to push the prongs over the stone. Then check AGAIN once the prongs are part way down and the stone no longer rocks. The small amount of extra time taken to check the seats can save a lot of heartbreak (or point break) later.
With pear or heart shaped stones, bend the v prong over the stone first. Then push the remaining prongs over the stone tightening it in the setting. Setting the stone in this manner allows the stone to move slightly as you bend the v prong, limiting the amount of pressure applied to the fragile tip of the stone.
On marquise shaped stones, bend the side prongs over the stone first, securing it into the setting. Then the v prongs are adjusted down over the points. The v prong is seen as protection to the fragile points rather than as something to hold the stone. Setting the stone in this manner limits the amount of pressure applied to the fragile tips of the stone.
You can use several methods to push the prong down onto the stone. You can use a prong pusher to gently roll the metal over the stone in the same manner you would push a bezel down. First, push on one side of the V, then the other. Alternate sides until the prong is tight against the crown of the stone.
Chain nose pliers with polished jaws can also be used. Place one jaw at the top of one side of the V, and the other jaw at the base of the opposite side of the prong. Gently squeeze one side down a little, then reverse the position of the pliers and move the opposite side. Work back and forth until the prong is down on the crown of the stone.
Another method using chain nose pliers is to place both jaws at the top of the outside edges of the V. Make certain the jaws are at the top of the prong well above the girdle of the stone. Angle the pliers to match the angle of the crown facets. Then gently squeeze the pliers together. As the pliers come together at the point of the V, the jaws will burnish the metal down onto the stone. Keep repeating the procedure until the metal is tight against the stone. As you work, excess metal will form between the pliers’ jaws, making a line at the point of the V. You should remove this excess metal with a file. This method works better on the thinner die struck v prongs.
Some jewelers cut a V in the top of the prong leaving two tabs to push over the stone. Then once the tabs are down the seam is soldered closed. This method works fine on diamonds, but cannot be used on most color stones. There is one danger in using this method on diamonds. If excess solder is used it can flow into the void providing clearance at the tip of the point. As the solder solidifies it contracts. This can cause the point to chip or break off.
Once the stone is set, trim and shape the outside of the prongs using a #6 needle file. Be certain the file has a polished safety edge to avoid the possibility of chipping or abrading the stone. Trim and clean up the inside edge of the V with a polished flat graver. Remove the file marks with an abrasive rubber wheel and polish.
Remember: Caution Is The Better Part Of Valor. If you feel uncertain while setting, STOP, take a deep breath, check all your steps, examine the setting with your loupe, then proceed. If you still feel uneasy, take a break, get a drink of water, relax a bit. Then re-examine the setting and proceed to finish the setting.
Follow these steps and you will not suffer a fate such as Juliet and her Romeo. “Parting is such sweet sorrow, Farewell, Farewell, I bid you Farewell….”