Identification and Durability of Lead Glass-Filled Rubies

Abstract

In early 2004, the GAAJ laboratory in Japan issued a lab alert about rubies they had seen that had large numbers of fractures filled with high-lead-content glass, which made them appear very transparent. Since then, large quantities of this material have reached international markets. This dramatic treatment is not difficult to identify with a standard gemological microscope, since it has characteristics similar to clarity-enhanced diamonds (flash effect, gas bubbles, etc.). However, locating filled cavities in reflected light is more challenging, as the surface luster of the filler is close to that of ruby. The filling material appears to be very effective in reducing the appearance of fractures. Durability testing of a few samples by highly skilled jewelers indicated that the filler was fairly resistant to heat exposure during jewelry repair procedures, but it reacted readily with solvents.

Surface and bulk 3D analysis of natural and processed ruby using electron probe micro analyzer and X-ray micro CT scan

“…Such fissure networks have been interpreted as the rutile fissures formed due to high temperature heat treatment. Similar, type of fissure lines are also observed during the heat treatment of ruby [25][26][27] and cobaltdoped glass-filled sapphires [28]. This type of fissure line is an indication of the heat treated ruby or corundum stone and also confirms the presence of Pb-filled fissures and rutile fissures in the corundum.…”

Red gemstone characterization by micro‐Raman spectroscopy: the case of rubies and their imitations

“…In fact, zircon occurs in North Vietnam rubies in association with calcite, dolomite, rutile, diaspore and phlogopite, as well as in Sri Lankan deposits with biotite flakes and rutile needles . In this case, the presence of glass infiltrations and zircon inclusions, the latter associated with baddeleyite, strongly suggests the hypothesis of glass filling and heating treatments for the sample R9 . In fact, recent studies on treated Madagascar corundum report the occurrence of subsolidus reactions of zircon inclusions with the subsequent formation of baddeleyite and the preservation of the euhedral morphology of the zircons.…”

Gemstone Enhancement and Its Detection in the 2000s

“…The filler proved relatively durable to heat (up tõ 600ºC), but it was easily etched by even mild acids such as pickling solution (McClure et al, 2006). This etching turned the filler white near the surface, rendering it quite visible.…”

“…Most had so many filled fractures that the flash effect was easy to see with magnification, although the red color of the ruby sometimes partially masked the orange flash (McClure et al, 2006; figure 18). Flattened gas bubbles and high-relief unfilled areas within the fractures were also readily visible with magnification.…”