21 steps to success

Tapered baguettes are probably the most difficult shape to set. They vary greatly because they are cut for weight, not optics or consistency. During setting, seats must be cut individually to fit each stone, which is difficult because round burs do not naturally cut flat, straight seats. Finally, tapered baguettes are the most delicate and fragile diamond shape, so be careful not to break them. Setting them requires precision, care, and patience. In this ninth installment of Practical Stone Setting, Alan Revere demonstrates how to set a pair of tapered baguettes as side stones in a cast mounting. The center stone, a marquise, will be covered in the next installment. There are different styles of settings for tapered baguettes, including round and rectangular prongs and half bezels, each requiring different procedures that can be executed differently. This project demonstrates two methods for creating seats in rectangular prongs using a variety of techniques.

1

This cast gold mounting has settings for three stones: two tapered baguettes and a marquise. Prior to starting the job, use a loupe to inspect the stones and the ring. Note damage on the job envelope.

2

As in real life, the two tapered baguettes supplied for this job are close, but not identical in measurement or shape. Place them side by side on a flat surface and compare them. Measure the stones and note how they differ. Both stones are within 0.1 mm in all measurements, but the profiles do not match as closely, with one stone deeper than the other. Measuring the settings, note that each has an opening of 4.6 mm between the prongs, perfect for a 5 mm stone because it allows for a 0.2 mm seat on each side. The large prong is 3.1 mm wide, which means that it will hold the stone but cannot provide side support. The small prong measures 2.4 mm, which will permit a closed seat with side support.

3

File the tops of the prongs, bringing them all into one flat plane for each setting. Using a small dab of stick wax, place each stone on top and look at it from above and from the sides. The stone should rest on top, with about 0.2–0.5 mm overlap on each end. Prongs can often be moved in or out a tad and the interiors filed away for further size adjustment.

4

Now visualize the point where the girdle will rest when the stone is dropped down into the setting. Set a pair of dividers to mark the distance between the tops of the prongs and the desired height, usually between 0.7–0.9 mm. Rest one leg of the dividers on top of the prong and transfer the measurement all around, so lightly that the finest sanding will remove it.

5

Beginning with the side bars, which connect the prongs, bevel both sides at 45 degrees. Use a flat needle file to bevel the top/outer half of each bar. File down until the top edge of the bevel almost splits the bar in half. Filing a little on one reflector, and then the next so that they progress evenly, finish with a very fine cut needle file.

6

Creating interior reflectors is both a necessity and a way to throw more light into the stone. These baguettes are cut with deep pavilions that won’t fit the space as is. Metal has to be removed from the interiors of the bars, while leaving a reflective flat surface at 45 degrees, to add sparkle. Gravers are best at this but require extra skill. An alternative is to use a long thin tapered bur. Either way, try to leave a flat angled plane on the interiors of the bars.

7

You will soon see that a round bur isn’t ideal for cutting a flat surface. So after roughing out the bevels, use a flat graver to true the planes, clean up the corners, and shave the metal down to a single flat and reflective bright cut.

8

A baguette’s corners are extremely fragile, so it is important that they float and not contact the metal. The small prong is wider than the stone, so cut the seat only on the interior of the prong, without breaking through at the edges, so the corners can float while the entire end is held in place. Using a 0.5 mm ball bur, make two small indentations at the ends of the line scribed on the inside of the small prong—make the indentations level and as close to the edges as possible without breaking through the plane. Bur about one-third into the prong for the ends of the seats.

9

Now use a 1 mm hart bur or a square graver to join the two indentations. Carve a level seat to hold the stone from above and below, without any contact at the corners. Use gravers as needed to clean up the smallest details on the closed seats.

10

Unlike the stationary small prong, the top of the large prong will be folded over to secure the stone. In preparation for moving the large prong, use a saw to free it from the rest of the casting. With a very fine 8/0 blade, carefully saw down the back of the prong to the girdle height.

11

With the large prong free, it can be folded over the top of the stone.

12

Use a saw to cut into the large prong from the interior, right on the line for the girdle. The depth of the cut depends on the length of the stone. In this case, cut no more than 0.2 mm deep into the prong.

13

Remove metal above the seat with either a file or a graver, leaving a very flat vertical surface. Check to see if the stone enters, and adjust to fit. Use a flat graver to clean up the bottom of the seat, leaving it at an angle to match the stone. A trick to encourage the metal to fold exactly as desired is to deepen the crease with a few passes of a knife graver.

14

Drop both stones in place and check the fit. The small end should slide into the closed seat and be held in place. The larger end should then drop onto the carved shelf of the large prong, snug against the vertical wall. There should not be space for the stones to wobble. Check that the stones feel stable; they should not rock when pushed from various points on top.

15

There are many ways to close a prong. Setters alternate between pushers, gravers, punches, pliers, beading tools, hammers, hammer hand pieces, and whatever else gets the stone in safely. Here, the ideal tool for closing the prongs is a common bench knife with a straight edge. Placed in the wedge between the ring and the prong, it is very effective for folding the metal.

16

With the knife firmly embedded against the prong, rock it slowly sideways, using the blade as leverage to fold the compliant metal. Proceed carefully, always examining the point of contact. Press the metal until it’s tight against the crown’s beveled end facet.

17

Tighten the metal, as needed, with a setting punch. Place the flat face of the punch on top of the large prong and use successive taps with a hammer to close gaps you see under the prong. Go lightly; remember the stones’ fragility. If necessary, sometimes you can fold the metal around the sides of the end of the stone to prevent it from slipping out of the prong.

18

Prior to filing the prongs to the desired shape, file the tops of the prongs level with the tables of the stones.

19

Next file the back of the small prong to make it thinner and more delicate. These should all be the same size, shape, and angle. This filing softens the hard rectangular prongs but defines them crisply.

20

Use a fine-cut flat needle to make small, crisp, flat bevels at 45 degrees, on the tops of all prongs.

21

Use a flat graver to carve a 45 degree bright cut on the tab of metal that was folded against the stone. The cut should be perpendicular to the facet of the stone it rests on. An alternative to engraving is to use a very fine flat needle file or abrasive wheel to refine the shape, followed by polishing.