An extraordinarily large undrilled light gray pearl (figure 1) was recently examined at GIA’s New York laboratory. Despite its impressive size (76.79 ct and 42.97 × 33.43 × 31.00 mm), the pearl exhibited an unexpectedly light heft, suggesting the presence of a hollow interior. Real-time X-ray microradiography (RTX) imaging revealed an unusual internal structure for a bead cultured pearl characterized by widely spaced concentric nacre layers separated by translucent veil-like organic material (figure 2), rather than the compact, continuous nacre typically observed in solid bead cultured pearls. The bead measured approximately 11 mm in diameter and was securely attached at one end of the pearl, with no internal movement or rattling detected when gently shaken. The thin nacre, measuring approximately 0.5 mm at its thickest portion, and hollow internal structure made the pearl extremely fragile.
Based on the gemological examination and the size of the pearl and the bead, the sample was identified as a South Sea bead cultured pearl. Patchy, uneven gray to brown material present underneath the surface appeared to be associated with an organic-rich internal structure; these features contributed to the pearl’s bodycolor. While some South Sea pearls may be cultured with organic or inorganic materials to intentionally produce larger baroque-shaped pearls, this was not the case for this sample (L.E. Cartier and M.S. Krzemnicki, “New developments in cultured pearl production: Use of organic and baroque shell nuclei,” Australian Gemmologist, Vol. 25, No. 1, 2013, pp. 6–13). In this instance, the mollusk may have been affected by unknown environmental or health factors, causing the pearl sac to inflate irregularly by gas or fluid accumulation, trapping organic materials between layers of nacre, ultimately creating a mille-feuille-like internal structure similar to a puff pastry layered with cream (L. Otter et al., “A look inside a remarkably large beaded South Sea cultured pearl,” Spring 2014 G&G, pp. 58–62).
While average sizes of South Sea bead cultured pearls range between 10 mm and 13 mm, exceptional examples may occasionally exceed 20 mm. This remarkable South Sea bead cultured pearl, with its extraordinary size and uncommon structures, provides interesting insights into a highly unusual growth pattern.
Emiko Yazawa is a senior analytics technician at GIA in New York.
An extraordinarily large undrilled light gray pearl (figure 1) was recently examined at GIA’s New York laboratory. Despite its impressive size (76.79 ct and 42.97 × 33.43 × 31.00 mm), the pearl exhibited an unexpectedly light heft, suggesting the presence of a hollow interior. Real-time X-ray microradiography (RTX) imaging revealed an unusual internal structure for a bead cultured pearl characterized by widely spaced concentric nacre layers separated by translucent veil-like organic material (figure 2), rather than the compact, continuous nacre typically observed in solid bead cultured pearls. The bead measured approximately 11 mm in diameter and was securely attached at one end of the pearl, with no internal movement or rattling detected when gently shaken. The thin nacre, measuring approximately 0.5 mm at its thickest portion, and hollow internal structure made the pearl extremely fragile.
Based on the gemological examination and the size of the pearl and the bead, the sample was identified as a South Sea bead cultured pearl. Patchy, uneven gray to brown material present underneath the surface appeared to be associated with an organic-rich internal structure; these features contributed to the pearl’s bodycolor. While some South Sea pearls may be cultured with organic or inorganic materials to intentionally produce larger baroque-shaped pearls, this was not the case for this sample (L.E. Cartier and M.S. Krzemnicki, “New developments in cultured pearl production: Use of organic and baroque shell nuclei,” Australian Gemmologist, Vol. 25, No. 1, 2013, pp. 6–13). In this instance, the mollusk may have been affected by unknown environmental or health factors, causing the pearl sac to inflate irregularly by gas or fluid accumulation, trapping organic materials between layers of nacre, ultimately creating a mille-feuille-like internal structure similar to a puff pastry layered with cream (L. Otter et al., “A look inside a remarkably large beaded South Sea cultured pearl,” Spring 2014 G&G, pp. 58–62).
While average sizes of South Sea bead cultured pearls range between 10 mm and 13 mm, exceptional examples may occasionally exceed 20 mm. This remarkable South Sea bead cultured pearl, with its extraordinary size and uncommon structures, provides interesting insights into a highly unusual growth pattern.
Emiko Yazawa is a senior analytics technician at GIA in New York.
