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I’VE NEVER VISITED M.S. Rau Fine Art Antiques Jewels, on Royal Street in New Orleans. But it runs some of the spiffiest ads. This recent one, “Beyond Blue: Tanzanite Ring,” The New York Times, April 18, 2021, is exemplary. Plus, it offers me a new word: pleochroic.

Tanzanite Ring, 22.00 Carats. The M.S. Rau website describes, “Possessing an entrancing deep violet-blue hue, an extraordinary 22.00-carat tanzanite is elegantly displayed in this ring. The oval-shaped jewel is perfectly accented by two nearly colorless shield step-cut white diamonds totaling approximately 1.00 carat, adding sparkle to this stylish creation.”

Tanzanite and diamond ring; price available upon request. This and the following images from M.S. Rau.

“Tanzanite,” M.S. Rau continues, “is one of the rarest gemstones in the world, found only in the African country of Tanzania for which it is named.” 

The Tucson Tanzanite Protocol. Because of its rarity, tanzanite has not been unknown in the conflict-stone trade. Indeed, as described in The Engagement Ring Bible’s “What’s Going on with Tanzanite?,” October 2, 2017, “Last November The Wall Street Journal ran a story exposing the fact that one of Osama Bin Laden’s close associates, Wadih el Hage, was selling tanzanite to buyers in the U.S. and Europe…,” tainting this gem with a terrorist conflict-stone image.

According to Tanzanite Foundation, “The Tucson Tanzanite Protocol was developed in 2003 to protect tanzanite and ensure an ethical route to market.” This is similar to other international understandings in the 1976 Diamond High Council and the 2000 Kimberley Process Certification Scheme. 

Though Engagement Ring Bible noted problems with the tanzanite trade, it said back in 2017, “If you’re buying from a reputable jeweller who can trace your tanzanite gem all the way back to the mine, then you most likely have nothing to worry about. And if your gem has been mined recently (i.e. after the new controls and safeguards had been implemented), it’s even more of a safe bet.”

Gem Etymology. M.S. Rau observes that “This rare stone presents the coveted pleochroic color phenomenon in which blue, purple, and violet are simultaneously displayed in a single stone depending on the angle of view.” I am reminded of the anamorphic perspective, as described in “Bois-Clair’s Turning Pictures,” an earlier offering from M.S. Rau. There, the angle-of-view differences were manmade. The tanzanite’s is Mother Nature’s artistry. 

Merriam-Webster describes pleochroism as “the property of a crystal showing different colors when viewed by light polarized in different directions.” M-W states that the English word is borrowed from the German Pleochroismus. Pleo traces back to the Greek pleion, hence our “plus.” Chroic is also from the Greek, chroous, “colored.”

M-W notes that pleochroism “was apparently introduced by the German mineralogist Wilhelm Haidinger, (1795-1871); see “Ueber den Pleochroismus der Krystalle,” Annalen der Physik und Chemie, Band 65, no. 5 (1845), pp. 1-29.” Thanks, M-W; interesting, but likely more information than we want to know.

Precious Opals. Not unrelated to pleochroism is iridescence, as exhibited by opals of the precious variety (so-called, though nowhere as rare as tanzanite). Wikipedia describes iridescence or play-of-color is “a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light.” Common opals do not display this play-of-color. 

And exceedingly uncommon is the Tanzanite and Diamond Ring offered by M.S. Rau; thus its captivating ad.

A Last-minute Puzzle! At a 6:06 a.m. check of this morning’s preloaded post (going live at 6:05 a.m.), the M.S. Rau website revealed this: “We’re Sorry. The tanzanite and diamond ring 22.00 carats you were searching for is/are not currently on our website. Below are similar pieces that might interest you.”

Interesting indeed and quite the puzzle. I have no idea why the ring was withdrawn at the last minute. ds 

© Dennis Simanaitis,, 2021 

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