 |
|
This 1.02-ct. diamond is colored by a pink residue in the large fractures that reach the surface through the crown. Photo by Elizabeth Schrader.
|
While diamonds typically are fracture filled to improve their apparent clarity, we have also seen stones in which a “filler” has been used for other purposes. For example, in the Spring 2003 Lab Notes section (pp. 38–39), the East Coast GIA Gem Laboratory reported on a 0.20-ct. round brilliant diamond that was filled for the sole purpose of producing a pink appearance. This diamond showed an uneven face-up color distribution, with the pink color confined to the eye-visible fractures. No attempt had been made to reduce the visibility of the large fractures, which showed areas of concentrated pink color in a fingerprint pattern when examined with magnification.
Recently, the East Coast lab received the 1.02-ct. “pink” round brilliant diamond shown in the figure for identification and origin-of-color determination. Like the diamond examined earlier, this stone exhibited uneven coloration, with the pink concentrated in large fractures; magnification of these fractures revealed a dried pink substance in a fingerprint pattern. However, further examination also revealed the flash-effect colors typically associated with the substances used for clarity enhancement. These flash-effect colors were visible in the smaller fractures and deeper parts of the large fractures, whereas the pink color was confined to the largest and most obvious fractures.
Energy-dispersive X-ray fluorescence (EDXRF) spectroscopy indicated the presence of lead and bromine. Both of these elements, which are not typically found in untreated diamonds, have been documented in diamond fracture-filling materials used for clarity enhancement (see, e.g., R. C. Kammerling et al., “An update on filled diamonds: Identification and durability,” Fall 1994 Gems & Gemology, pp. 142–175). From this evidence, we concluded that the diamond was indeed fracture filled to improve its clarity. Since the colorless filling was seen deeper in the fractures than the dye, we assume that the diamond was first fracture filled, and then dyed. This is the first diamond we have seen that showed both types of treatment.
Siau Fung Yeung and Thomas Gelb
GIA Gem Laboratory, New York
|
