AGTA GTC's Laboratory Update for November 22, 2005
In this message…
- Passport to Obscurity
- Christie's Sets New Auction Records
- Peace of Mind with an AGTA GTC Report
- AGTA GTC on the Web
Passport to Obscurit
Obscurity is a lonely place, right next door to oblivion.
While a passport typically conjures up images of freedom, the open road and travel to exotic locales, not every destination is five-star. This point was driven home during the examination of a group of yellow sapphires recently sent to the laboratory for identification.
The lot consisted of several yellow sapphires of graduated weight, each with similar shape, facet arrangement and face-up color. It appeared likely that all were intended for a single piece of jewelry.
In gems of this type, inclusions are often sufficient to immediately identify the host as a natural sapphire, as well as prove or disprove heat treatment. When present, a 3160 infrared peak is also important evidence of natural, untreated origin in yellow sapphires. With but one exception, all the sapphires in the group contained obvious visual micro-evidence of natural origin, along with moderate to strong 3160 peaks in the infrared, both tickets to paradise.
One sapphire, however, showed no obvious inclusions and no telltale 3160 peak, immediately raising an alarm. This meant it would require additional examination consisting of a detailed microscopic inspection using a combination of fiber-optic and darkfield illumination, with polarized light, if needed. Careful scrutiny would be necessary if a decision was to be reached as to the full identity.
Microscopic search parties were sent out throughout the stone on a facet-to-facet search. All reported back empty-handed. Except one. As the stone was rocked to-and-fro, a weak flash of light winked from the abyss. Zooming in revealed a miniscule, inconspicuous heat-damaged inclusion with an associated mirror-reflective discoid decrepitation halo (Figure 1). While at just 0.01 mm in diameter (as measured with an eyepiece micrometer), this inclusion was certainly tiny, it was all that was needed to both eliminate the possibility of synthetic origin and prove heat treatment.
Figure 1. Destination unknown… Although relatively small and inconspicuous at roughly 0.01 mm. diameter, this heat-treatment damaged crystal with its diagnostic discoid decrepitation halo (also produced by heat treatment) is all the proof needed to destroy the natural reputation of its host yellow sapphire. Photomicrograph © John I. Koivula/microWorld of Gems. |
Separate identification reports were requested for every stone and all except one received natural, unheated reports. While we do not know the fate of this individual gem, we suspect that when the client studied the reports, the guilty stone was pulled and a natural replacement found. The treated stone is probably now destined for a lesser piece of jewelry, or perhaps it will simply be placed somewhere in a drawer, cast aside and forgotten.
Inclusions are passports, identification papers. From the transparent calcite rhombs in Burma rubies to the rutile arrows in Sri Lankan sapphires, these tiny disturbances so often provide entreé to a better place. But as this tale tells, inclusions may also be tickets to a less-than distinguished future.
When inclusions provide proof of natural origin, they allow entry to paradise. But when the reverse is true, when they prove a gem to be treated or synthetic, they can be passports to obscurity. And obscurity is but a short walk from the abyss of oblivion.
Christie's Sets New Auction Records
At the recent Christie's Magnificent Jewels sale in Geneva, Switzerland, several new records were set. Foremost among these was a crown set with 1,000 carats of white and yellow diamonds and pearls. It sold for SFr.7,972,000 (US$6,138,440), the highest price for a piece of jewelry sold this year, as well as the most expensive crown ever sold at auction in the world.
The Régente, a large historic pearl from the French Crown Jewels, sold recently at Christie's Geneva for $2.5 million. This pearl measures 17.6 x 20.8 x 28.5 mm and weighs approximately 302.68 grains (75.67 carats). Photo by Denis Hayone – Diode SA; courtesy Christie's; used with permission. |
Another exceptional item was the large historic pearl from the French Crown Jewels, La Régente, the fifth largest gem-quality pearl known to exist (Lot 354). It realized SFr.3,628,000 ($2,516,360). It was previously sold by Christie’s Geneva in 1988 for $859,100. According to Christie's:
La Régente, the highly important pearl of incredible size and weight, 302.68 grains, was given by Emperor Napoleon I (1769–1821) to his second wife Marie-Louise in 1811, and originally set in a tiara. In 1853, Napoleon III (1808–1873) put the pearl into a corsage as a wedding present for his future Empress and wife, Eugénie de Montijo. In 1887, when the French Crown Jewels were sold at auction in Paris, the pearl was given the name, La Régente and was purchased by Fabergé of St. Petersburg for Princess Zenaïde Youssoupov (1861–1939), heir to a Russian fortune.
Sold as part of the same collection as La Régente was a unique jewel with more than 1,500 carats of pearls, along with almost 1,000 carats of diamonds and sapphires. It fetched SFr.2,148,000 ($1,653,960). This modern two-part natural pearl necklace was created to set off La Régente at its center. The collection totaled SFr.19 million ($14.7 million) for eighteen pieces, well ahead of pre-sale expectations of $8 million.
Give the Gift of Peace of Mind with an AGTA GTC Report
It is no secret that technological advances have led to an explosion of ever-more sophisticated synthetic and treated gems. Consumers have a broad range of purchase possibilities and if they lack confidence in our jewelry and gemstone products, they will look elsewhere.
One of the best ways to inspire consumer confidence at the point-of-sale is to present gemstones with an AGTA Gemological Testing Center Identification or Origin Report. These attractive reports can be the difference between the choice of a fine gemstone gift, or some other product.
We would remind our customers that with the holiday gift-giving season rapidly approaching, the demand for our gem-testing services will also increase. Beat the rush and submit your gems now. This will ensure that you have professional reports at the ready when it comes time to close a sale.
The AGTA Gemological Testing Center Identification Report provides a perfect point-of-sale tool for consumer peace of mind. |
AGTA GTC on the Web
A number of clients have asked us to consider making our gemological bulletins available to a wider audience. Towards that aim, over the past few months we have built a website specifically for the AGTA Gemological Testing Center. It is now live and offers a complete archive of our e-mail bulletins, along with a full description of the lab and its services. See it at www.agta-gtc.org or link from AGTA’s regular site, www.agta.org.
The new AGTA-GTC website offers the most up-to-the-minute gemological news, along with a full description of the lab and its services. |
