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Keshi pearls consist of solid nacre, and tend to have high luster as a result. All nacre colors typical of the mollusc under cultivation may be represented among keshi pearls harvested from the same, but in the case of Akoya pearls a larger portion of keshi is usually grey than of bead-nucleated pearls.
The iridescent nacre inside a nautilus shell Nacreous shell worked into a decorative object. Nacre (/ ˈ n eɪ k ər / NAY-kər, also / ˈ n æ k r ə / NAK-rə), [1] also known as mother-of-pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed.
After a bead is inserted into the oyster, it secretes a few layers of nacre around the bead; the resulting cultured pearl can then be harvested in as few as twelve to eighteen months. When a cultured pearl with a bead nucleus is X-rayed, it reveals a different structure to that of a natural pearl.
They are not to be confused with cultured pearls, which are real pearls created through human intervention. Materials used to create imitation pearls include glass, plastic, and mollusc shells. As an alternative, some plastic beads are coated with a pearlescent substance to imitate the natural iridescence of nacre or mother of pearl.
White pearl necklace. A pearl nucleus or a bead for cultured pearl is a sphere (usually) or other shape (occasionally) formed only by cutting and polishing a nacreous shell used to accommodate the nacre secreted from a graft of mantle tissue, that eventually forms the centre of a beaded cultured pearl. [2]
Although these are a variety of cultured saltwater pearls, the amount of time that the pearls are cultured dramatically increases the depth of the nacre, and the likelihood of producing a baroque pearl. Most Tahitian pearl farm harvests, which, for example, produce more than 40 percent baroque and semi-baroque pearls.
One example is the site of Oued Djebbana in Algeria, for example, where an N. gibbosulus bead was found; at the time the shell was used there, this site was at least 190 km away from the sea. [ 2 ] Shell ornaments were very common during the Upper Paleolithic , from 50–40,000 years ago onwards, when they spread with modern humans to Europe ...
A selection of glass beads Merovingian bead Trade beads, 18th century Trade beads, 18th century. A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under 1 ...