Most people understand that gemstones are from the earth, and that they have been there for a long time. But a long time is such an abstract concept. However, when Gübelin Gem Lab is able to give the age of a gemstone using radiometric dating, that abstract concept becomes very real. How long is a long time? Think in terms of millions of years, not hundreds of thousands. Here is an excerpt from the May 12, 2016 issue of the Gübelin Newsletter #46, on determining the absolute age of Kashmiri sapphires.
Kashmiri sapphires determined to be 25 million years old
Last fall, for the first time ever, the absolute age of a high-value gemstone has been determined. Our geochemical specialist Klemens Link used radiometric dating on the in-house Laser Ablation ICPMS facility. The method and results are published in the latest issue of the Journal of Gemmology, Vol 34, Issue 8. Meanwhile, age determination is applied regularly in our lab on rubies and sapphires, supporting the distinction of African and Sri Lankan sapphires from the Burmese and Kashmiri ones.
The determination of the exact age of Kashmiri sapphires, however, was not yet undertaken, until the Gübelin Gem Lab initiated a research project jointly with Prof. C. Liu, and Dr. C. Zhang of the Institute of Geology and Geophysics, Chinese Academy of Sciences in Beijing. Zircon crystals included in samples from the Gübelin Reference Collection have now been analysed by LA-ICPMS in the Gubelin lab, and by high-resolution SIMS at the IGGCAS in Beijing. The respective uranium-lead ages are 26.8 (±3.8) million years, and 24.97 (±0.22) million years, mutually confirming the results.
This is exciting news for all of us at Omi Gems and Omi Privé. Our Kashmiri Sapphires are among our favorite gemstones. To be able to imagine them in terms of their real age makes them even more magnificent in our eyes.
The platinum Omi Privé ring shown on the left and at the top of this post features a 3.43 carat Kashmir Sapphire accented with French-cut tapered diamond baguettes and round brilliant-cut diamonds.