Pearl Nucleus Manufacturing

Manufacturing the Pearl Nucleus
A pearl nucleus is manufactured from freshwater mussel shell which has been worked into a perfect polished sphere.
The Nucleus is an Essential part of Perliculture
  • The nucleus of a pearl, although it is not typically visible in a harvested pearl, is extremely important in the culturing process.
  • The nucleus is the core of the pearl, that the pearl sac will use to "guide" the shape and help produce the cultured pearl.
  • Without high quality nucleus it is impossible to create high quality pearls.
The Best Nuclei come from Shells Collected from the Mississippi River
  • The bead material used to create the nucleus has historically been derived from freshwater mussel shells found mostly in the Tennessee River, in the Mississippi River Basin.
  • As available stock of natural shell has dropped significantly and as the popularity of cultured pearls has risen, other sources of shell have been explored.
  • Chinese freshwater shell is now used to a considerable extent, as is the illegal use of Giant Clam shell (Tridacna gigas). The Giant Clam is protected by the CITES treaty and should not be used to produce cultured pearls.
  • Pinctada maxima shell from Australia and The Phillippinnes has also been used to produce nuclei, at much lesser extent.
The Shells are Processed in Asia
  • The shell harvested from these rivers is collected, sorted and then exported to Asia to be worked or processed.
  • This process involves cutting the shells into strips and then into cubes.
  • These cubes are then shaped into perfect spheres by first edging/grinding them by hand, then grinding with plates, tumbling in an acid solution, and finally polishing.
  • Throughout the process, the beads are carefully inspected to ensure a perfect shape.
  • These finished nuclei are then separated by size and quality.

The Finished Nuclei are Graded then Sold
  • The finished product falls into different quality ranges in a similar fashion as pearls themselves. There are three qualities commonly sold on the market today. Akoya pearl production demands the highest-grade bead due to nacre depth.
  • The top-grade bead is one that is perfectly white, with as little possible "banding" (striations).
  • A slightly lower-grade bead with have some slight discoloration, and a low-grade bead with have dark bands of calcium carbonate buildup appearing as rings around the nucleus. This banding is referred to as striation.
  • These low-grade nuclei are commonly used in the production of darker cultured pearls such as Tahitian pearls.
  • Any visible banding on the nucleus, even if the pearl is medium grade and the banding is light, can be detected in a light-color, medium to thin nacre pearl by the presence of "blinking" when examining and rotating the pearl.

Visiting a Pearl Nucleus Factory with Pearl Paradise​

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