synthetic corundum.7, ruby, Verneuil, gems

A.E. Alexander investigates the existence and identifying features of “reconstructed” ruby, reporting an experimental rod made from natural ruby fragments and a faceted stone independently judged to have a similar origin. The inquiry arose from repeated encounters with rubies submitted as reconstructed material that proved to be synthetic, leaving Alexander doubtful whether reconstruction was commercially or technically genuine. To test the possibility, he assembled 14 carats of natural ruby chips selected for good color and identifiable natural inclusions, including rutile needles, and submitted them to A.K. Seeman of Linde Air Products Company. Instead of being fused directly into a mass suitable for faceting, the chips were ground to 200 mesh and made into a rod approximately 1½–2 millimeters in diameter and 41 millimeters long. A section was examined longitudinally with a binocular microscope and subsequently prepared as a thin section for petrographic study. Fusion produced a slight loss of color and eliminated recognizable evidence of the original mineral inclusions, even during examination at 450× and 900×. The rod contained spherical and irregular gas cavities, cometlike inclusions with distinct tails arranged in a broadly fan-shaped pattern, and curved growth lines transverse to its length. Its c-axis lay approximately 70° from the rod’s length, while examination between crossed polarizers revealed occasional grains oriented differently from the surrounding mass. During this investigation, a dealer submitted a 1.28-carat faceted ruby that initially resembled an early Verneuil synthetic. Examination by immersion in alpha-monobromonaphthalene instead led Alexander to identify it as reconstructed. Following donation of the stone to the Gem Trade Laboratory, it was examined in July 1948 by B.W. Anderson and E.J. Gübelin at Gübelin’s Lucerne laboratory; both agreed with that interpretation. Features described include peculiar swirl markings, some sharply terminated, four distinct undulating veils, gas cavities, and other inclusions resembling those encountered in natural corundum. Recorded properties were refractive indices of 1.760–1.767, specific gravity of 4.00, bright red fluorescence under ultraviolet radiation and X-rays, and the characteristic ruby absorption spectrum. The article presents these observations as evidence that reconstructed ruby can exist in both rod and faceted forms, while showing that the fusion process can create features resembling synthetic corundum and destroy recognizable inclusions inherited from the natural starting material.