The Tridacninae subfamily of giant saltwater clams consists of two genera: Hippopus and Tridacna. These bivalve mollusks live only in the shallow waters of coral reefs in the tropical parts of the Indo-Pacific Ocean (E. Strack, Pearls, Rühle-Diebener-Verlag, Stuttgart, 2001, p. 60). They are known to produce white to cream non-nacreous pearls, with yellow or orange pearls less commonly found. Tridacninae pearls frequently exhibit a porcelain-like surface with a flame structure caused by stacked layers of aragonite lamellae in a crisscross fashion. The sheen-like effect occurs when those lamellae interact with light (H.A. Hänni, “Explaining the flame structure of non-nacreous pearls,” Australian Gemmologist, Vol. 24, No. 4, 2010, pp. 85–88). Pearls with such characteristics are known as porcelaneous pearls.
A 4.77 ct near-round white Tridacninae pearl (see above) recently examined by the author displayed a well-arranged flame structure consisting of a wide base with spiky ends radiating outward from the apex of the pearl. Microscopic examination under fiber-optic light revealed a remarkable feature. A dramatic pseudo-chatoyancy occurred over the luminous flames, creating the appearance of an eye staring back at the observer. Pearls with prominent flame structures and high sheen often contain striking features.
The Tridacninae subfamily of giant saltwater clams consists of two genera: Hippopus and Tridacna. These bivalve mollusks live only in the shallow waters of coral reefs in the tropical parts of the Indo-Pacific Ocean (E. Strack, Pearls, Rühle-Diebener-Verlag, Stuttgart, 2001, p. 60). They are known to produce white to cream non-nacreous pearls, with yellow or orange pearls less commonly found. Tridacninae pearls frequently exhibit a porcelain-like surface with a flame structure caused by stacked layers of aragonite lamellae in a crisscross fashion. The sheen-like effect occurs when those lamellae interact with light (H.A. Hänni, “Explaining the flame structure of non-nacreous pearls,” Australian Gemmologist, Vol. 24, No. 4, 2010, pp. 85–88). Pearls with such characteristics are known as porcelaneous pearls.
A 4.77 ct near-round white Tridacninae pearl (see above) recently examined by the author displayed a well-arranged flame structure consisting of a wide base with spiky ends radiating outward from the apex of the pearl. Microscopic examination under fiber-optic light revealed a remarkable feature. A dramatic pseudo-chatoyancy occurred over the luminous flames, creating the appearance of an eye staring back at the observer. Pearls with prominent flame structures and high sheen often contain striking features.
