How to Drill and Set South Sea Cultured Pearls

By Stuller | August 15, 2012

Recommended Tools:
(12-2132) Devcon two part epoxy, 1 oz. set
(28-0732) 0.8mm drill bit
(28-0700) Micro motor drill
(Sizes 5mm – 20mm, 28-0710 thru 28-0725)
Brass Pearl Holders, Pair

(35-1797) Micrometer
(48-1067) Ring Clamp
Water-based marking pen
Sticky notes

  1. Finding and Marking the Face of a Pearl
    The face of a pearl is the side you would like to see when the pearl is set. To find the face, examine the pearl surface and decide what side is most appealing. Looking at the shape of the pearl, blemishes, and suitability to the jewelry piece when choosing the face. Mark the face with the letter F using a marker. Use the Micrometer (with water-based pen marker on both pads) to find the center points or axis on which the pearl is to be drilled.
  2. Marking the Drill Site
    After marking the face of the pearl, determine the drill site and mark the drilling point on the pearl with a D. For full-drilled pearls, find the balance point and mark the opposite side. They need to be drilled from the outside into the center. Never drill a pearl straight through.
  3. Determine the Drill Depth
    Check the drill bit to be sure it is securely positioned in the chuck and that the bit is undamaged and straight. With a marker, mark a depth line on the drill bit for how deeply you wish to drill in to the pearl.
  4. Secure the Pearl in the Vise
    Select the cup size to suit your pearl. Be careful not to allow the edge of the cup to damage the pearl. If you are drilling an oversized pearl or a baroque pearl, use padding in the cups to secure the pearl. Screw the cups firmly into the pearl vise.
  5. Align the Pearl
    Once the pearl is in the vise, line up the drill site with the bit. To check for accurate positioning, with the vise in the locked position, orient the flat of the drill toward you and bring pearl onto the drill. For full-drilling of pearls, move the chuck to rotate the pearl around to the other side to line up the bit with the opposite drill mark. If the pearl lines up onto drilling point and is straight and balanced at both positions, it is ready for drilling. If your drill bit is not lining up with one of your marks, loosen your pearl and rotate it in the cups for perfect alignment. If you are still unable to line up your marks, then remove your pearl and check the marks. You may have to remark your drill sites.
  6. Drill the Pearl
    Stand when drilling or move the drill close to you so you can see both sides of the pearl. Turn the machine on, and bring the drill bit down to the pearl. Make sure the vise is in the locked position. Using light pressure for drilling, allow the drill to cut the skin of the pearl. Gently support the pearl with your forefingers and thumb and drill to your depth mark. For half-drills, drill from one side only, remove the pearl from the cups, and tap out the dust. For full-drills, slide the vise all the way back and rotate 180°. Check that the vise is in the locked position and drill as before. Remove the pearl from the cups and tap out the dust.
    NOTE: Never drill a pearl all the way through from the start position, as the bit can flex and be deflected.
  7. Sizing the Drill Hole
    If the pearl is to be post-mounted, hold the pearl securely and, with a hand drill fitted with 0.8mm bit, open the guide hole using light pressure on the drill. Ensure this follows the line of the first drilling. Security of the pearl is ensured by a tight fit between the pearl and the post; thus the drill hole must be sized in such a way that the pearl has to be screwed onto the post. The post should be of maximum length; shorten only if absolutely necessary.
  8. Gluing the Pearl
    Remove dust from the drill hole (if drilled through, use compressed air; if drilled from one side, tap firmly to clear the hole). The recommended glue is Devcon two-part, 5-minute epoxy (12-2132). Mix the glue on a sticky note and insert glue into the drill hole. Apply a small amount of glue to the post. Wipe away any excess glue with a tissue impregnated slightly with denatured alcohol. Secure the pearl and mounting in a ring clamp (48-1067). Tie the clamp with a rubber band tied several times around the ends of the clamp.
    NOTE: The entire process should not take more than two minutes as the glue will start to set.
  9. Drying
    Glued items should sit for 24 hours in a humidity-free environment before removing the jewelry from the clamp. It is advisable to save the original paper with your glue mixture until your jewelry is completely cured. This will help ensure that your mixture is correct.
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