Practical Stone Setting, Part 22
The procedures in this article are standard practices for bench jewelers at this time. If not executed properly, however, they can cause harm. Neither the author nor publisher is responsible for injuries, losses, or damage that may result from the use or misuse of this information.
Setting gemstones in bezels can be easy or difficult, depending on the stone size, metal thickness, and, of course, the skill of the jeweler. More difficult than round or oval settings, square bezels require exact fitting and burring, firm control of the punch, and precision filing and finishing. In this example we are setting a 5 mm square synthetic ruby into a cast sterling silver ring.
Alan Revere, director of the Revere Academy of Jewelry Arts
1. Select a stone to fit the setting. It should be snug all around. If it hangs up and does not drop in all the way, some metal must be removed from the sides. Depending on where and how much, gravers and burs are used to trim the metal with precision. The stone should drop between the vertical walls and sit on the diagonal seats, which matches the angle of the stone’s pavilion. The stone should sit on all four seats evenly. In this case the cast ring already has a seat. If making this setting in metal, consider using telescoping square tubing, the inner for the seat and the outer for the walls. In some cases the seat must be carved from thicker metal using burs and gravers.
Fig. 2. Mark the height with a pair of dividers.
2. Place the stone into the bezel and use a pair of dividers set at 1 mm to inscribe a light line around the setting. Establish this line first, before you make any adjustments. It will serve as an approximate height of the girdle and also as a constant reference after filing begins.
Fig. 3. Stone at proper height in bezel
3. Use a large flat file to adjust the height of the bezel. Although the surface is small, needle files are not nearly as effective as a large flat hand file. File across the top from all sides as you lower the metal evenly. Use the scribe marks as a reference. Reduce the height until the top of the stone sticks out. Between 25 percent and 50 percent of the crown should protrude above the bezel. Setting the stone deeper results in extra work during both setting and cleanup.
Fig. 4. Use a large flat file to bevel the bezel.
4. Because the metal is so thick, several small steps are added to “encourage” it to move more easily. First, file an angle on the top so there is less metal to move. Use a large flat file to file the top of the bezel outward diagonally on all four sides. Use long even strokes and do not wobble. Leave a miter in all corners, where the angled bevels meet. File the four sides at about 20 degrees below horizontal.
Fig. 5. Use a 0.5 mm ball bur to crease the corners.
5. Check the walls and seat, removing any obstacles with a graver or bur as needed. Use a tiny 0.5 mm ball bur to score and weaken the thick metal at the creases before moving. Start in the vertical corners at the seat. Bur up and down, creating a gully in the metal at the corners. This metal should be removed because the fragile corners of the stone will float in these grooves while the sides are held in place on the seats. Make even gouges into the metal at all four vertical corners and horizontally along all four sides where the wall meets the diagonal seat. This is one of the ways to weaken the metal where you want it to move. Scrape the spinning bur back and forth lightly along the corners, deepening the groove to weaken the metal.
Fig. 6. Saw a very small nick on the corners.
6. Here is the last little adjustment to make the thick bezel walls fold in and over the stone. Use a saw blade or graver or even a small bur to nick the corners from above. This is definitely not slitting the corners to make tabs out of the four sides, which is amateurish and never looks good. Instead, make a millimeter-deep nick exactly at the corners to weaken the metal and get it moving in the right direction when force is applied. Do not saw farther than the saw blade’s depth.
Fig. 7. Use a setting punch to close the metal over the stone.
7. With the work securely held in a vise, you are ready to move metal inward. Use a chasing hammer and a setting punch (made of tool steel about 100 mm long with a rough flat face about 1.5 mm x 2.5 mm). Place a wax “setting snake” over the stone to hold it in position. Place the face of the setting punch at the side of the corner, on one of the bevels. Adjust the punch to about 45 degrees and tap downward, rather than inward. Move the metal a tiny bit over the stone and stop. Now place the punch on the other side of the same corner and move it inward too. Go back and forth, working alternately on the two sides of two opposite corners, pinching the metal a little bit just at the corners. Do not move the middle of the walls in yet. Alternate opposite corners until the stone is tight. Then use the punch to move the middle of the walls inward, as the hardened metal on the corners do not move. Maintaining the same 45-degree angle throughout the process, use the punch to create a perfectly flat bevel at about 45 degrees all around.
Fig. 8. Smooth the surface with the punch at a higher angle.
8. Now raise the punch to about 70 degrees and tap downward, closing the metal in farther and evening out the surface. Pay special attention to the inner edge, making sure you see contact between the metal and the gem. This angle should approximate the bevel of the stone’s crown.
Fig. 9. File the top facets.
9. Use a large fine-cut file to remove excess metal and even out the surface. These facets are very difficult to file correctly, and using a large file enables one to take long strokes, leaving a flatter plane. Take the four surfaces down slowly, making sure to maintain an even flat plane on each top facet of the bezel. Stop when the four facets are flat and there is a crisp mitered corner diagonally between them. Do not let the file touch the stone.
Fig. 10. Use a fine grit sanding stick on the top edges.
10. Now take the top surfaces down to a finer finish in preparation for polishing. The challenge is to keep the recently filed surfaces flat and not let them get rounded. Using a sanding stick works fairly well if the paper is flat and tight. Otherwise it will round the top edges. Be sure to maintain the crisp corners with diagonal miters.
Fig. 11. Use fine abrasives for final finish before polishing.
11. An alternative to sanding is to use the flat end of an abrasive wheel. This is also a good way to go to the highest grit before polishing. Rubberized abrasives come in all shapes and grits. Here is a very fine flat Shofu® disc that can be used on large flat surfaces.
12. The final touch is to clean up the inner edge of the metal against the stone and create a reflective bright cut. The standard way is to use a flat graver to trim and shave the metal very slowly down to an even line with a polished reflector. Gravers require special skills, which are beyond the scope of this lesson. The less precise method is to use a polished pointed burnisher to rub the inner edge of the metal where it meets the stone. The tool imparts a polish without any trimming. At all times and with both methods, great attention needs to be paid to the tip of the tool, which should not damage the stone.
Fig. 12. Use a flat graver for the final bright cut.
With the work firmly supported, place the corner of a graver flat against the metal, angled diagonally, and shave off as little as possible with each pass. Pull the graver back as you burnish on the recoil. Then push forward and shave, burnish, shave, burnish, until the sides are crisp and meet at sharp mitered corners.
Fig. 13. Completed square bezel
13. During finishing, buffing, and polishing, great care must be taken not to round the crisp facets and corners of the setting. For this reason, it is best to take the surfaces up to the highest level of abrasive prior to polishing. Hard felt wheels are better for polishing flat surfaces. Use a light touch, keep the buff moving, and avoid wearing down the recently completed bezel.
© 2010 Revere Academy of Jewelry Arts; first publication rights assigned to JCK magazine.