Distracting features in this ruby could easily cause gemologists to misidentify the stone. Learn more about how we unmasked this tricky synthetic.
The conjuror or con man is a very good provider of information. He supplies lots of data, by inference or direct statement, but it's false data.
— James Randi (Magician)
Introduction
The art of misdirection is essential to a good magic trick. By directing the audience’s attention towards one thing, the magician can distract from another, and then wow the crowd with a big reveal. To figure out how a magic trick is done, one must pay attention to the right details, while ignoring the distractions.
This is true in gemology as well. Recently, a great reminder of this came through our laboratory.
Figure 1. The 17.86 ct ruby that is the subject of this report. Photo: Ronnakorn Manorotkul/Lotus Gemology
General Properties
A client submitted a 17.86-ct ruby cabochon, which was declared as a heated Mozambique ruby (Figure 1). The stone was transparent, although with some eye-visible inclusions, which is not surprising for a ruby of such a large size. A series of standard tests was run on the stone. We noted that the stone displayed very strong red appearance in long-wave fluorescence, and a strong chalky red appearance in short-wave fluorescence, which is common for a heated ruby, although a bit unusual for a Mozambique stone (Figures 2–3). Analysis with FTIR did not reveal any diagnostic features.
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| Figure 2. The ruby was examined under a standard long-wave/short-wave UV light box A. The stone displayed strong red fluorescence in long-wave UV. B: In short-wave UV, the stone displayed strong chalky red fluorescence. Photos: Ronnakorn Manorotkul/Lotus Gemology |
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Figure 3. The ruby was examined under a standard long-wave/short-wave UV light box A. The stone displayed strong red fluorescence in long-wave UV. B: In short-wave UV, the stone displayed strong chalky red fluorescence. Photos: Ronnakorn Manorotkul/Lotus Gemology
Microscopic Features
Under the microscope, we noted several interesting inclusions. There were a few clouds of very fine particles (Figures 4–5) that resembled partially dissolved silk. The stone also contained many fingerprints with white, frosty crystals, some with immobile gas bubbles (Figure 6). Some fingerprints had drippy, melted areas (Figure 7). This stone had the appearance of having undergone high-temperature heat treatment.
Figure 4. Fine particles could be seen in the stone. Photo: E. Billie Hughes/Lotus Gemology
Figure 5. Some of the fine particles formed more dense “rain-like” streams that could superficially resemble partially dissolved silk. Photo: E. Billie Hughes/Lotus Gemology
Figure 6. The stone contained several fingerprints made up of frosty white crystals, many with immobile gas bubbles inside. These are sometimes referred to as flux “icicles.” Photo: E. Billie Hughes/Lotus Gemology
Figure 7. This melted fingerprint with drippy channels provided further evidence that the stone was heated. Photo: E. Billie Hughes/Lotus Gemology
We took a closer look at the fingerprints, focusing on the surfaces with a fiber-optic light. Often heated rubies display some glass at the surface openings of fissures, either as a byproduct of flux heating or from glass filling, but careful examination of this stone failed to reveal this (Figure 8). Something was not quite right. While the ruby did look heated, the features did not seem consistent with Mozambique ruby as declared. The dotted appearance of the silk did not match the platelets we expect to see in heated Mozambique material, and the crystals looked different too.
Figure 8. Examination of fingerprints cut through on the surface revealed no signs of glass filling. Photo: E. Billie Hughes/Lotus Gemology
This gemologist started considering other possibilities. Could this be a synthetic? Most synthetic rubies that come through our laboratory are flame-fusion stones. Usually, these stones are extremely clean compared to natural stones, so their lack of inclusions is a red flag. This stone was different because it was full of inclusions, however it didn’t resemble either a natural ruby or the common flame-fusion synthetics. A perusal of our sample collection and Hyperion inclusion database (Hughes, 2021) suggested that it could be a flux synthetic.
This would explain the variety of inclusions. The fine particles were not partially dissolved silk, but streams of fine flux droplets, sometimes called “rain” (Hughes et al., 2017). The frosty white crystals were primary flux, which have been reported in Kashan synthetic rubies, and are sometimes described as flux “icicles” (Gübelin & Koivula, 2008 and Watanabe, 1987).
Chemistry
Chemistry was run with ED-XRF to confirm this hunch.
| Element | PPMA |
| K | 108 |
| Ca | 37 |
| Ti | 244 |
| V | 26 |
| Cr | 957 |
| Fe | 3 |
| Ga | Below detection limit |
The results supported our suspicions. With no gallium (Ga) detected, low iron (Fe) and high titanium (Ti) compared to other synthetics, this stone was a good match for a Kashan flux synthetic (Schmetzer, 2007).
Considering the chalky short-wave fluorescence, as well as the melted inclusions, we also believe this stone was heated.
Conclusion
Why would you heat a synthetic ruby? It’s possible that the treater thought the ruby was natural and heated it like they would a natural stone. The treatment could also have been carried out to obfuscate the evidence that the stone is synthetic, as has been done in the past with quench-crackled and flux healed flame fusion synthetics (Crowningshield, 1980 and Koivula, 1983).
While most synthetics stand out for their high clarity (and sometimes too good to be true colors), it is stones like these that can prove trickiest to detect (Singbamroong, 2007 and Krzemnicki, 2016). A dusting of particles and a few melted crystals can provide almost enough distraction to fool a gemologist. But careful observation and thorough testing will unmask this sleight of hand.
About the Authors
E. Billie Hughes visited her first gem mine (in Thailand) at age two and by age four had visited three major sapphire localities in Montana. A 2011 graduate of UCLA, she qualified as a Fellow of the Gemmological Association of Great Britain (FGA) in 2013. An award winning photographer and photomicrographer, she has won prizes in the Nikon Small World and Gem-A competitions, among others. Her writing and images have been featured in books, magazines, and online by Forbes, Vogue, National Geographic, and more. In 2019 the Accredited Gemologists Association awarded her their Gemological Research Grant. Billie is a sought-after lecturer and has spoken around the world to groups including Cartier and Van Cleef & Arpels. In 2020 Van Cleef & Arpels’ L’École School of Jewellery Arts staged exhibitions of her photomicrographs in Paris and Hong Kong.
Notes
An expanded version of this article will appear in the June issue of The Australian Gemmologist.
References
- Crowningshield, R. (1980) Corundum observations and problems, Gems & Gemology, Vol. 16, No. 9, pp. 315–319.
- Gübelin, E. J. & Koivula, J. I. (2008) Photoatlas of Inclusions in Gemstones, Volume 3. Basel, Switzerland, Opinio Publishers, pp.171–175.
- Hughes, E. B. (2021) Hyperion inclusion database. Retrieved January 23, 2025, from
https://lotusgemology.com/resources/hyperion-inclusion-repository - Hughes, R.W., Manorotkul, W., & Hughes, E.B. (2017) Ruby & Sapphire: A Gemologist’s Guide, RWH Publishing/Lotus Publishing, Bangkok, pp. 279–287.
- Koivula, J. (1983) Induced fingerprints, Gems & Gemology, Vol. 19, No. 4, pp.220–227.
- Krzemnicki, M. (2016) The challenge: Identification of Ramaura synthetic ruby, Facette, p. 14.
- Schmetzer, K. & Schwarz, D. (2007) The causes of colour variation in Kashan synthetic rubies and pink sapphires, Journal of Gemmology, Vol. 30, No.5/6, pp. 331–337.
- Singbamroong, S. (2007) Heat-treated Kashan grown flux synthetic ruby, Gems & Gemology, Vol. 43, No. 2, pp. 175–177.
- Watanabe, K. (1987) Inclusions in flux-grown crystals of corundum, Crystal Research and Technology, Vol. 22, No. 3, pp. 345–355.