After poor quality Freshwater Cultured Pearls are weeded out, the processors begin the drilling process. There are two different drilling types, full-drilling and half-drilling. Full drilling is a hole that is completely through a cultured pearl. This type of drilling is used for pearl necklaces and bracelets, where the string must pass completely through the pearl. Drilling is extremely delicate work, as the pearl is drilled using two drill bits from each side. This is because drilling with one longer drill bit would risk damaging the nacre when it extends out through the opposite side. One slip and the pearl can be completely destroyed. Half-drilled pearls are used for earrings, rings, pendants, tie tacks, brooches and other types of similar pearl jewelry. This type of hole is only drilled through half of the pearl.
Pearls with a noticeable blemish on one side can but cut and then half-drilled in order to make them useful. For instance, for a pearl ring, the pearl may have been blemished on the side of the pearl that is attached to the ring. Instead of discarding this pearl, the blemish can be cut off and then the half-drilled hole can be drilled on the flat side of the pearl. The pearl is attached on the flat side to the ring and the result is a beautiful piece of pearl jewelry.