AGTA GTC's Laboratory Update for May 1, 2007
In this message:
- Auction Action
- Burmese Jadeite
- Treated Sapphire with Multiple Personality Disorder
- Secrets in Sapphire: Mystery Inclusions in Rutile Silk
- AGTA GTC Mobile Laboratory in Las Vegas
- Upcoming Lectures
Auction Action
Christie's New York's Magnificent Jewels sale on April 25th, 2007 shattered two important records. Lot 262, the Baroda Pearls, a two-strand natural pearl necklace with ear pendants, brooch and ring en suite fell for a stunning $7,096,000. This is an auction world record for a natural pearl jewel. The previous record was set by Christie's Geneva in November 2004 at $US3.1 million, for a two-strand natural pearl necklace.
But this was not all. Lot 261, a 22.66 ct cushion-shaped Kashmir sapphire pendant, more than doubled the previous record for a sapphire, selling for a whopping $3,064,000 ($135,216/ct). This gemstone featured an AGTA GTC Origin Report and the pre-sale estimate was $250,000–350,000. The previous record of $3,031,000 ($48,871/ct) for the 62.02 ct. Rockefeller Sapphire was set in 2001. That sapphire hailed from Burma.
This 22.66 ct Kashmir sapphire set a new auction record, selling for $3,064,000 ($135,216/ct). Photo: AGTA GTC. |
In addition to these record setters, a pearl and diamond necklace was submitted to the AGTA GTC prior to auction. Originally thought to be cultured pearls and with a pre-sale estimate of $12,000–18,000, they proved to be natural pearls. Sale price? $135,000. Value of an AGTA GTC Pearl Report? Priceless.
Following testing at the AGTA GTC, this natural pearl necklace greatly exceeded its pre-sale estimate. Photo: AGTA GTC. |
Burmese Jadeite
A piece of jadeite jade brought in for testing recently was intriguing in a couple respects. First were the inclusions. While one does not normally think of distinctive inclusions in jadeite, this gemstone possessed a clear cluster of crystals, including many which broke the surface and displayed a much higher luster than the surrounding jadeite. Micro-Raman analysis identified these as zircon, which had been previously identified in jadeite by John Koivula and Tom Moses in 1998 (Gems & Gemology, Vol. 34, No. 1, p. 45).
A cluster of zircon inclusions in jadeite jade. Photo: Richard W. Hughes/AGTA GTC. |
The same group of zircons seen in reflected light breaking the surface and displaying high luster. Note also the small (black) pits and microfractures, which suggest bleaching. Photo: Richard W. Hughes/AGTA GTC. |
In contrast, the surface of an untreated jadeite shows only major cracks. Absent is the network of tiny microfractures created by bleaching. Photo: Richard W. Hughes/AGTA GTC. |
FTIR of polymer-treated jadeite performed with both the DRIFTS and beam condenser methods. |
In addition to the zircon inclusions, the specimen displayed a network of fine cracks that suggested it had previously been bleached. Bleaching is the first stage in the common B-jade process where jadeite is bleached to remove foreign matter from its pores and then the tiny micro-fissures are impregnated with either a wax or polymer, greatly improving both color and clarity.
Such treatment is typically unmasked by reference to FTIR spectra. When we first checked the FTIR spectrum via the DRIFTS method (see FTIR Intrigue), large polymer peaks were found. A recheck with the beam condenser method revealed the same polymer peaks, but at reduced levels.
Treated Sapphire With Multiple Personality Disorder
Following on our previous report of a ruby with multiple personality disorder, we tested a sapphire showing the same schizophrenia. The sapphire weighed close to 7 ct and showed orange fluorescence with a blue rim in LW UV, and chalky blue fluorescence in SW UV. The pavilion surface and parts of the crown was covered with a multitude of minute fingerprints induced by heat, as well as surface pits. When a white diffuser plate was used, color was found concentrated on the surface, exactly following the facet pattern, indicating lattice ('surface') diffusion with titanium. EDXRF showed 0.185 wt% Ti (usual Ti concentrations are approx. 0.01%).
In addition to the unusual color pattern, a group of small feathers were seen on the surface, suggested prolonged heating at high temperatures. On a lark, we performed a LIBS test and found a distinct Be peak with LIBS at 313 nm. The result? The gemstone was not only titanium diffused, but also beryllium diffused, yet another corundum with multiple personality disorder.
Diffused light reveals concentrations of color at the surface and facet junctions, suggesting lattice diffusion. Photo: Hpone-Phyo K. Nyunt/AGTA GTC. |
Shallow fingerprints in the same gemstone, caused by prolonged high-temperature heating. Photo: Hpone-Phyo K. Nyunt/AGTA GTC. |
Secrets in Sapphire: Mystery Inclusions in Rutile Silk
From the beginning of my gemological studies in 1979, I have been intrigued by inclusions and none have provided greater fascination than rutile silk. I never tire of gazing at these gossamer-like strands in untreated ruby and sapphire.
Initially, I was attracted to the brilliant colors; later, I learned to appreciate their structural details, noting that what I first regarded as single crystals were actually microscopic twins with tiny re-entrant angles at the broad ends.
Over the past few years, I've noticed a further hidden detail. Virtually all exsolved rutile needles large enough to be clearly resolved with my microscope (up to 70x magnification) show tiny daughter crystals at the broad end, implanted directly in the re-entrants.
What are these hidden mysteries? Mostly likely, they are impurity phases forced out of solution with the rutile, probably something like hematite (trigonal Fe2O3) or ilmenite (trigonal FeTiO3). We are currently in search of a specimen where these daughter crystals are both large enough and close enough to the surface for analysis.
High magnification reveals that well-formed rutile silk generally has tiny daughter crystals growing at the broad ends. Untreated blue sapphire. Photo: Richard W. Hughes/AGTA GTC. |
Again, tiny daughter crystals are clearly visible at the broad ends of rutile arrows in this untreated blue sapphire. Photo: Richard W. Hughes/AGTA GTC. |
For more on rutile silk, see Following the Silk Road: Rutile Silk in Corundum.
The AGTA GTC Mobile Laboratory in Las Vegas
It's Vegas time, and once again the AGTA GTC stands ready to provide outstanding and prompt service both before and during the show.
Submit early for best service
It is always advantageous to get your testing done prior to the show. This will allow you to have your goods ready for sale when the doors open.
- Submissions received by the AGTA GTC on or before Tuesday, May 22nd will be available for pickup at our NY office by Friday, May 25th for those who need their gemstones for the show
- Please note that during the show, no express service will be offered at the NY Laboratory; New York submissions during the show will have a slightly longer turnaround time (7–10 business days) since so many of our staff will be at the show
Services at the show
The AGTA GTC Mobile Laboratory will be in full swing at the JCK Show – Las Vegas 2007, offering a range of gemological services, including:
- Identification reports for all kinds of gemstones, including the identification of clarity enhancement fillers
- Country-of-origin reports for ruby, sapphire and emerald
The AGTA Pavilion has special dates and times, opening and closing one day before the main JCK show. Located in the AGTA GemFair™ Cultured Pearl & Jewelry Pavilion, the AGTA GTC Mobile Laboratory is open as follows:
- Dates: Thursday, May 31st to Monday, June 4th
- Hours: 10:00 AM to 6:00 PM on May 31st and 9:00 AM to 6:00 PM from June 1st–4th
The AGTA GTC Mobile Laboratory will deliver reports to clients at the show within 1–2 days; services will be available during normal show hours.
Show fee schedules
Utilizing the services offered during the show ensures convenience and rapid turnaround. Our show fee schedules can be downloaded in PDF format at the links below:
- Mobile Laboratory Fee Schedule for AGTA Members
- Mobile Laboratory Fee Schedule for AGTA GTC Associate Program Members
- Mobile Laboratory Fee Schedule for Nonmembers
Our regular fee schedules are visible at this link:
Upcoming Lectures in Las Vegas
AGTA GTC staff will deliver the following lectures during the show:
Las Vegas, NV, May 30–31, 2007, AGTA GemFair™ Las Vegas
- Solid Steps to Successful Colored Gemstone Sales
Douglas K. Hucker, American Gem Trade Association
Wednesday, May 30, 2007, 3:30–4:30 PM
Venetian Hotel and Casino, Room Toscana 3609, Level Three
AGTA's Chief Executive Officer explores the critical components of a dynamic and successful colored gemstone jewelry presentation. What motivates your customer to buy color? What are their major concerns when doing so? Learn the basic components that must be included in every presentation to dramatically improve your success rate. Identify your most powerful sales tools, including a thorough discussion of the AGTA GTC Colored Gemstone Report, and the critical part they play in the sales presentation.
- Update from the AGTA Gemological Testing Center
Dr. Lore Kiefert, AGTA Gemological Testing Center
Thursday, May 31, 2007, 9:00–10:00 AM
Venetian Hotel and Casino, Room Toscana 3609, Level Three
The AGTA laboratory comes across many materials and treatments before they hit the market. Knowing about these new developments on the gemstone market, as well as having an idea what to look for, will help you make the right decisions in your buying and selling of gemstones. AGTA's scientists focus on colored gemstones.
- Increase Sales by Empowering Your Team with Knowledge
Loretta Castoro, AGTA Gemological Testing Center
Thursday, May 31, 2007, 3:30–4:30 PM
Venetian Hotel and Casino, Room Toscana 3609, Level Three
AGTA GTC is launching training opportunities for your use in staff development. In this preview session, you have sample segments of gemological seminars, which include how to empower your staff to comfortably engage in communicating about colored stones with your clients. These seminars build confidence by providing the most current gemstone knowledge available in the industry.
