This can be open or closed depending on the jeweller’s desired effect.
Today, this word is used in jewellery to describe the portion of a ring where a single gemstone or collection of gemstones sit. If the design has lots of areas where light can pass through, it is said to be an open gallery and if the top of the ring is solid, it is said to be a closed gallery.
In days gone by, the gallery referred to a strip of metal that circled the gem and was cut into a design resembling the top of a castle wall, where the raised parts were bent over the gem to act as prongs. As gold and silver are very malleable metals, jewellers can often apply very intricate designs to the gallery.
Although the term is primarily used in association with rings, effectively the area where any gemstones sit on, i.e. earrings, bracelets, pendants and necklaces, is in fact a gallery.
Its name I assume comes from the fact that a gallery is somewhere that displays pieces of precious art, as this is precisely what the gallery in a piece of jewellery is intended for.
