The Gemological Institute of America (GIA)’s Tokyo laboratory recently checked a vivid red stone mounted in a ring that was submitted for an identification and origin report. Weighted around 2.14 carat, the stone showed two strong specific absorption lines in the blue area through a handheld spectroscope, and its gemological properties confirmed ruby.
According to GIA, the ruby fluoresced strong red to long- and short-wave ultraviolet light. It contained natural-looking angular milky clouds (figure A), unusual wispy veil-like milky clouds (figure B), strong angular graining (figure C), and triangular negative crystals containing flux-like materials and minute bubbles (figure D). Although the pattern of milky clouds gave the appearance of a natural origin, the wispy veil-like clouds and triangular flux-like inclusions are characteristics of flux-grown synthetic ruby.
GIA determined the stone’s chemical nature by using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). The analysis revealed lower concentrations of magnesium and gallium and much higher concentrations of lanthanum, platinum, and lead than those found in natural rubies. Vanadium was not detected. These chemical features, especially the absence of vanadium and the detection of lanthanum, platinum, and lead, were abnormal for natural ruby. The inclusions and trace element chemistry, particularly the presence of lanthanum, suggested a Ramaura flux-grown synthetic ruby. The inclusions were consistent with those in Ramaura flux-grown rubies except for the presence of natural-looking milky clouds.
How lanthanum and lead are incorporated into this synthetic ruby is not clear, as there were no obvious inclusions that could be tested (such as particles or flakes within the clouds). However, the natural-looking clouds were clearly formed by partial enrichment of lanthanum and lead within this Ramaura synthetic ruby, said GIA.
“Surprisingly, such milky clouds and flux inclusions could be confused with heated natural ruby and might cause misidentification. Careful observation of inclusions in the stone and chemical analysis were both needed to confirm that this was a laboratory-grown ruby,” GIA added. (Photo courtesy: GIA)
21-08-2024
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