Feature Gems & Gemology, Summer 2010, Volume 46, No. 2

X-ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls

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X-ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls

The distinction of natural from cultured pearls traditionally has been based on X-radiography. X-ray computed microtomography (μ-CT) has recently been applied to gain more insight into pearl structures. Using this technique, this article presents features observed in a selection of natural pearls and beaded and non-beaded cultured pearls. Based on these observations, μ-CT is shown to be a powerful tool for pearl identification.

DATA DEPOSITORY

Supplementary Videos (see below)
Summer, 2010

Figures 1a and 1b
Two Natural Pearls

Two natural pearls, samples mxt 3 (freshwater; a) and mxt9 (saltwater; b); for details and explanation, see table 1 and figure 3.

Figure 2
A Beaded Cultured Pearl

A beaded cultured pearl, sample mxt 14b (saltwater); for details and explanation, see table 1 and figure 4.

Figures 3a, 3b and 3c
Two Non-beaded Cultured Pearls

Two non-beaded cultured pearls, samples mxt 1 (freshwater; a) and mxt 61_14 (saltwater; b). Also included is a short movie showing the rendered model of the cavity structure (“moustache”) in the center of sample mxt 1 (c); for details and explanation, see table 1 and figures 5 and 6.

Figure 4
A Non-beaded Cultured Pearl

A non-beaded cultured pearl with a complex structure, sample mxt 21_1 (saltwater); for details and explanation, see table 1 and figure 8.