As with all Pearls, it's essential to appreciate and understand that pearl drilling is extremely delicate work. If the driller is not careful the nacre can become damaged. A single slip can completely destroy the pearl.
There are two different drilling types: full-drilling and half-drilling. Full drilling is a hole that goes all the way through a cultured pearl. This type of drilling is used for pearl necklaces, where the string must pass completely through the pearl. Half-drilled pearls are used for pearl earrings, rings, pendants, tie tacks, brooches, and other types of similar jewelry. The hole is drilled through half of the pearl, allowing the Akoya pearl to be mounted on the gold setting of the jewelry. The same system of drilling is used for other pearls as well as for Akoya pearls.
Pearls with a single blemish on one side can be cut and then half-drilled in order to make them useful. For instance, for a pearl ring, the pearl may have had an original blemish on the side of the pearl that is attached to the ring. Instead of discarding this pearl, the blemish can be cut off the pearl, and then the half-drilled hole can be drilled on the cut side of the pearl. The pearl is attached on that side to the ring and there still remains a beautiful piece of unblemished pearl jewelry.