In the Orient and elsewhere, when it is considered desirable to mount a pearl so that it shall not turn, especially when only one part of the pearl is perfect and that is to remain outside, the drill hole is sometimes made square, that is to say, drilled round and then reamed out with a small saw until it becomes square, when a square wire is inserted; or else the pearl is first drilled with a tiny round hole and this is then reamed out until it is triangular, when a triangular wire is introduced. This method is sometimes used for studs or ring-settings.
In setting pearls with points or claws on the wire or band of a ring, the pearls are drilled only half way through. A gold pin is then inserted, and sometimes a thread is cut into the pearl itself; it is secured by means of gum mastic or some other strong gum. Occasionally, to add greater strength, a side pin is put in, so that the pearl is drilled with two bits of metal, which penetrate the one side in a perfectly straight line and the other at an angle of about twenty-five or thirty degrees (this is called side-pegging). This gives more strength and firmness to the pearl itself, and prevents it from twisting or twining and becoming loose. Sometimes the pearl hole is drilled so that the opening is that of a screw-thread, in order to hold it to the earring, the stud, or the ring. The gold pin which is inserted to attach the pearl to the ring or stud has a screw-thread also, and the peg or pin is screwed on as well as secured.
An ingenious method, termed “keying,” for securing the peg in pearls to be set on rings or studs, consists in drilling a hole half through the pearl and then two smaller holes or grooves on each side of the first. Cutting tools of a T-shape are now introduced into the aperture and worked about until the pearl is undercut all around, so that when a peg with a cross-piece is inserted, the latter can be turned within the pearl until it sets at right angles with the widest part of the aperture. In this way the peg is permanently secured and cannot slip out.
The fact that in recent years more pearls have appeared in necklaces that are irregularly bored, that the bore holes are so large that they are plugged with mother-of-pearl, or that one meets with pearls in which a plug has been placed in the side immediately in the center between the two drill holes, is due to the fact that the great demand has resulted in the destruction of many oriental ornaments in which the pearls were drilled in various ways, as well as in the destruction of the different Magyar and other semi-official jewels of eastern Europe.
The most primitive known drills were the flint drills, made by the North American Indians by chipping chert or flint-like minerals to a fine point. With these rude instruments a large, irregular hole was made, which generally measured several times the diameter of the fine drill hole made by a modern pearl driller with an improved drill. The Indians are also said to have used hot copper drills for boring holes.
The earliest, and still a very general and perhaps the best way of drilling pearls, is by means of the bow- or fiddle-drill. This method has been used in a more or less perfected form by all the aboriginal peoples of the New World from Iceland to Tierra del Fuego. But as none of these peoples were familiar with fine, hard steel, they scarcely ever succeeded in making drill holes as fine as those that can be produced by the use of tempered steel. By the latter means, pearls half an inch in diameter are often drilled entirely through with an aperture no larger than a thin bit of straw.
The largest and finest pearls are frequently drilled with the smallest holes, as the slightest loss in weight means a diminution in value. Then, too, a pearl with a small drill hole is not so liable to shift on the string, and thus is less likely to cut the silk thread which holds the pearls together.
It would be difficult to enumerate all the tricks to which some jewelers now resort in order to utilize every fragment of a pearl they can lay their hands on. Some of them are wonderfully clever at reconstruction, but to the woman who loves pearls, nothing can take the place of the soft, beautiful, round gem, with its natural surface.
In sorting pearls for the smaller necklaces, it is customary to open up a number of dozen bunches of the East Indian pearls as they are sent from the East, strung, the ends fastened together in bunches, and then sealed. These pearls are placed on a table and are first arranged according to color and luster on the sorting board. They are then grouped according to size and graduation, the greatest care being exercised in the selection for color, luster, and form. In this way ten necklaces may be re-strung into ten others, the necklaces probably being improved as regards selection, or else better arranged for the uses to which the jeweler wishes to put them.
In the case of the larger necklaces, it frequently requires many years of selection and arrangement before one becomes perfect enough to pass the criticism or suit the fancy of the jeweler.