Flush Setting Diamonds

Practical Stone Setting, Part 21

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.

Alan Revere, director of
the Revere Academy of Jewelry Arts

This is either the easiest or most difficult setting of all. As simple as it looks and as captivating as it appears, the flush setting is either a dream or a nightmare.

If you know what you are doing and you can really control the tools, flush setting takes minutes. But if you cut the seat too deep, too wide, too low, or any of a number of other “too’s,” it simply will not work and may not even be salvageable. This style of setting must be executed with exacting precision, or it won’t work at all. Also, keep in mind that these techniques are not safe for soft gems because of the pressure required. Use flush setting for diamonds, sapphires, and rubies, as well as some synthetics like CZs.

Fig. 2. Plate with 2 mm hole.

Also called a “rubbed” or “gypsy” setting, this style has gained popularity because of its minimalist design, which is sleek and contemporary. Also, because the procedures are quite simple and quick, flush setting is also economical. It is ideal for spraying a cluster of stones of different sizes, as well as for use as a focal point or center stone. Flush setting can also be executed on square and baguette shapes, with much greater effort and time. Straight flat seats and sharp corners are nearly impossible with burs and require the use of gravers.

The basic idea in flush setting is to drop the stone into a tight hole and then rub a little metal over the girdle all the way around. As long as metal encircles the stone, very little is required. As little as 0.02 mm overlap all the way around will hold a stone securely.

Fig. 3. Use a bud bur to open the top and taper the hole.

Examine the stone for damage and see how thick the girdle is. For this type of setting, it is best to use brilliant-cut stones with thin to medium girdles, because they match the shape of hart burs, with a 90-degree corner.

1. As an exercise, begin with a sheet of copper 1.5 mm thick and a 3 mm round stone. Lay out cross hairs with a pair of dividers to locate the center.

Fig 4. Place the stone over the hole with sticky wax.

2. Drill a 1 mm pilot hole, followed by 2 mm. Flip the plate over and use a bur to remove the flashing on the bottom side.

3. This is the first of several very exact procedures. Use a 3.2 mm bud bur to open up the hole and taper it. The hole through the metal will be tapered because of the shape of the bur, which is actually a little too large to enter all the way. As the bur enters and then goes deeper, the size of the opening increases. It is critical to make the opening the correct size, which is also difficult to describe. Simply stated, the opening should be cut so that the stone will almost enter.

Fig. 5. Stone sitting on top of tapered hole.

4. Transport the stone using sticky wax. Deposit the stone and check the fit.

5. With the stone in place, it is clear that the girdle is entirely outside the hole. This fit is critical. The stone must rest at the very edge of the hole all around, with the girdle on top. And if the hole were any greater, the stone would drop in.

Fig. 6. Cutting the seat with a hart bur.

6. Here comes the next very critical step: using a hart bur to cut the seat sideways into the tapered hole. In this demonstration, a 2.7 mm hart bur is inserted to the contact point in the tapered hole. This depth allows the bur to make contact all around at the correct height for the seat. The depth of the stone is very important. It needs to be high enough so only a little metal needs to be rubbed over to hold it tight. If the hole is too deep, then too much metal movement will be required, and it will be difficult to get the stone tight.

Spin the bur and make the smallest nick, a few hundredths of a millimeter into the wall of the tapered hole, all the way around.

Fig. 7. Seat is visible all around the tapered hole.

7. Remove the bur and note the precise seat cut very near the top of the hole. It is level and even in depth all the way around. (Note an alternative method, which is to use a smaller hart bur and make nicks all around the hole, connecting them into one seat.) The setting really demands precision at this point. If the cut is too deep, the stone will swim around and be very difficult to capture when burnishing. If the seat is too high or low, it also will not work. When learning, you may need to do this several times before you see success.

Fig. 8. Stone in place for entry.

8. The stone will still not enter. In fact, the opening has not changed and the stone has to be tilted to insert it into the opening. Place the stone on top with one side tipped and about to enter the setting.

Fig. 9. Use a brass pusher to press the stone into the opening.

9. Press the stone into the setting. Use any of a number of pushers, beginning with the softest: your finger, followed by your fingernail, then perhaps a wooden dowel or handle, a plastic pusher (make one from a toothbrush), a copper pusher or a brass pusher like this one. Use the tool to apply a little pressure, slowly. Press down firmly on the table as the stone squeezes tightly through, pushing the metal aside slightly. Apply more pressure as needed. The stone should slide or snap into place, sometimes with an audible click. Use this technique on hard stones only. Depending on the size, the stone may be flush on top or stick out. Smaller stones do not need to stick out above the metal. Larger ones, like this 3 mm stone, have crowns that are too tall to fit within the opening and must protrude to be set this way.

Fig. 10. Tighten and polish with a burnisher.

This procedure requires that the opening be just right and there is very little room for error. If the hole is too small, the stone will not enter, no matter how hard you push. So don’t try. On the other hand, if the opening is too large and the stone slides in with no friction, then it will be loose and hard to set because the metal is not close enough to move against the stone.

Fig. 11. Completed flush setting.

10. The final critical step is using a polished round tapered burnisher to capture the stone and tighten the metal. The idea is to use a very polished tool, made easily from an old bur or beading tool, which is tapered into a ball end, then polished. The burnisher pushes outward to smooth the metal and, at the same time, a small sliver of metal gets pushed onto the stone all the way around because of the curved tip of the burnisher.

Insert the burnisher into the opening and, with very light downward pressure and a little pressure outward, rub the inside of the hole above the stone. At first there will be some wobble as the stone still has room to move around. After a few passes all the way around, the metal should close in over the top of the girdle.

11. The finished flush setting is simple and elegant. The table can be above the level of the metal, as in this case, or perfectly flush with the metal surface. With the polished beveled reflector, the bright stone and setting contrast dramatically with the surrounding matte surface.

© 2010 Revere Academy of Jewelry Arts; First publication rights assigned to JCK magazine.