Half-Drilled
A pearl drilled only partway through, so it can be cemented onto a post. How pearls are mounted in studs and rings.
The hole stops at the centre of the pearl. A metal peg is glued in, and a small cup often supports the base.
Because the drilling does not break the far surface, the pearl presents an unbroken face, which is why half-drilling is used wherever a single pearl is on show.
The weak point is the adhesive. Water, soap and solvents break it down over time and the pearl works loose.
When you are buying
Any half-drilled pearl will eventually need re-gluing. That is normal maintenance, not a defect, and a jeweller will do it inexpensively. Just take rings off before washing your hands.
Full-Drilled
A pearl drilled all the way through so thread can pass. How every strand pearl is prepared.
Finger Ring
A ring set with a pearl, usually a single dome-backed or button pearl in a protective setting.
Stud
An earring that sits directly on the lobe, held by a post through the piercing.
Bezel Setting
A metal rim wrapped around the edge of a stone or pearl to hold it. The most protective setting there is.