New Field Research Confirms Tibetan Andesine

We publish courtesy of Gems & Gemology eBrief

Authors: Ahmadjan AbduriyimBrendan M. Laurs

An international group traveled to Tibet in late September 2010 to investigate the controversial origin of red andesine from China. The group was organized by coauthor AA and hosted by miner Li Tong and his wife Lou Li Ping. It also included Richard Hughes (Sino Resources Mining Corp., Hong Kong), Flavie Isatelle (geologist, France), Christina Iu (M.P. Gem Corp., Kofu, Japan), Thanong Leelawatanasuk (GIT, Bangkok), Young Sze Man (Jewellery News Asia, Hong Kong), and coauthor BML. Our goal was to examine three reported Tibetan andesine localities located close to one another 90 minutes southeast of Shigatse: Bainang, Zha Lin, and Yu Lin Gu.
AA visited the Bainang mine, reportedly Tibet’s principal source of andesine, in 2008. Most of the mining there took place in 2005-2008 and was organized by Li Tong. Unfortunately, despite having official permission from the Chinese government and police escorts, a powerful local lama would not allow us to visit the deposit.

Local people using simple hand tools mined the Zha Lin deposit in 2006-2008, reportedly producing approximately 2 tonnes of andesine. We saw a series of shallow pits within the medium-gray silty soil that underlies alluvium consisting mainly of shale and mudstone. We recovered andesine from two small pits (120 cm maximum depth) we dug in the mine area, and from two out of three pits dug in random areas of undisturbed alluvium 30-50 m upslope from the mining area. As seen previously in Tibetan andesine, all the rough material was rounded and ranged from pale to deep red with a few pieces containing bluish green areas.

The Yu Lin Gu occurrence is hosted by an alluvial fan located approximately 2 km up-valley from Zha Lin. Nearly 200 kg of andesine has reportedly been picked up from the surface by locals since 2006. We recovered andesine from the surface or slightly below the surface in loose silty soil, but did not find any stones when we dug pits into the alluvial fan. The range of color and degree of rounding of these pieces were similar to those from Zha Lin, but many had less-saturated coloration.

We were unable to verify whether Yu Lin Gu is a true andesine deposit because we could not find samples at depth. Our discovery of andesine within pits dug in random, previously unexplored areas near the Zha Lin mine, however, provided proof of a genuine Tibetan andesine deposit. The original source rock for the andesine was not evident in the area, and may have previously eroded away.

Ahmadjan Abduriyim
Gemmological Association of All Japan – Zenhokyo, Tokyo

Brendan M. Laurs

Editor, Gems & Gemology, GIA Carlsbad
Note: This report may be downloaded in PDF form here
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From Gems & Gemology: Fall Issue Features Retrospective of the 2000s

We publish courtesy of GIA’s Gems & Gemology GIA Insider

Every decade promises change, and the first decade of the millennium did not disappoint. The Fall 2010 issue of Gems & Gemology, which mails Oct. 22, looks back on 10 eventful years in the gem and jewelry industry. Building on retrospectives from the Spring 1990 and Winter 2000 issues, this special volume provides an overview of the major developments in marketing and distribution, gem localities, treatments, and analytical techniques.
De Beers’s abandonment of its single-channel distribution role. The rise of online retail. Confronting the issue of “blood” diamonds. These are just a few of the decade’s developments that changed the way diamonds, colored stones, and pearls are bought and sold. Russell Shor and Robert Weldon review the impact of these market forces in the lead article.
Next, Dr. James Shigley and coauthors summarize the new diamond, colored stone, and pearl sources of the 2000s, as well as known localities that remained active. The article includes a stylish wall chart of major world gem-producing regions, a comprehensive table of colored stone localities, and supplemental resources in the online G&G Data Depository.
A decade that began with high-pressure, high-temperature (HPHT) color enhancement of diamonds also witnessed the beryllium diffusion of sapphire and many other challenging and controversial processes. Shane McClure heads a report on the sophisticated new gem treatments of the 2000s and methods of identifying them.
The final article, by Dr. Christopher M. Breeding and coauthors, examines the technological innovations that have shaped gemology in recent years. These include chemical microanalysis techniques, real-time fluorescence and X-ray imaging, and nanoscale analysis.
“These four retrospective articles deliver timely knowledge for every gem and jewelry professional,” said G&G editor-in-chief Alice Keller. “In chronicling the past decade, they offer essential insight on the state of the industry today.”
In addition, a retrospective article on synthetics and simulants will appear in the Winter 2010 issue of G&G.
To purchase the Fall 2010 G&G or to subscribe, visit the GIA Store, contact Circulation Coordinator Martha Rivera at martha.rivera@gia.edu or call toll-free (800) 421-7250, ext. 7142. From outside the U.S. and Canada, call (760) 603-4000, ext. 7142.

Industry Analysis: Rough Market Stays Hot, Polished Diamonds Lukewarm

We publish courtesy of Gems & Gemology’s G&G GIA Insider

Author: Russell Shor, Senior Industry Analyst

The rough diamond market continues to run much hotter than the polished market. The Diamond Trading Company’s Oct. 4-8 sight, initially estimated at $425 million, increased to nearly $500 million as clients requested additional allocations.
The DTC held the line on prices, but rough sold at tender auctions from other producers and the DTC subsidiary Diamdel was reportedly up 10% or more from the previous month.
Alrosa, the world’s second-largest producer, announced rough sales of $2.53 billion for the first nine months of the year, an increase of nearly 50% over 2008 (the last “normal” year). However, price increases accounted for more than half that figure. The company expects its 2010 rough sales to total $3.3 billion (compared to DTC’s estimated $5.8 billion). Alrosa’s production was mined in Russia, except for about $450 million worth from Angola’s Catoca mine.
At odds with the continued high demand for rough is a very cautious polished market worldwide. As noted in last month’s Insider, buyers at the Hong Kong show were walking away from high polished prices that attempted to recoup up to half the rough increases. In the U.S., retailers are downgrading qualities and sizes to keep costs down.
U.S. retail jewelry sales have been running an estimated 3% ahead of 2009 levels, less than the 4% to 5% forecasted earlier this year.
Deloitte and the International Council of Shopping Centers predict that holiday retail sales overall will hover around 2% to 3% over last year, with jewelry falling within that range.
ZIMBABWE: Kimberley Process delegates will meet next month to determine whether to certify exports of rough diamonds from Zimbabwe’s Marange deposit. Zimbabwe’s government recently auctioned 1.3 million carats under KP supervision. The prices realized, coupled with reports from the area, indicate that the proportion of gem-quality diamonds is more than double the initial KP estimate of 5%. And the amount of near-gem material (destined for India) is reportedly 35%, which rivals Argyle. This means that as much as half the Marange production could be cuttable.
The huge size of the deposit, spread over hundreds of square miles, makes it difficult to properly survey — one reason Marange took the diamond world by surprise. Some estimates claim it could produce 40 million carats annually, which would make it the world’s most productive diamond area.
Ongoing concern over Zimbabwe’s human rights record and the fact the KP approved the rough diamond exports despite a U.S. ban on trade with that nation, is prompting talk of a two-tiered Kimberley Process system.
Proponents of this plan, which the U.S. State Department will reportedly promote at the November KP meeting, say the current system is too narrowly focused on “conflict” diamonds — diamonds sold by rebel groups to fund wars — and does not take into account human rights abuses by recognized governments of producing nations (i.e., Zimbabwe). They are also frustrated with the KP requirement of a unanimous vote by its members before it can initiate any action.
Opponents argue that a two-tiered KP system would create a “favored” diamond track for large producers such as De Beers and Rio Tinto and for branded Canadian diamonds, while casting unwarranted suspicion on diamonds from smaller producers.
MACRO: Spending Pulse noted that through the first nine months of 2010, online retail sales for all merchandise categories posted a 7.8% year-over-year growth. Online jewelry sales for September, however, fell 5.9% against the previous year. The luxury market research group also noted that September was the only month this year to record negative growth for the online jewelry category. Blue Nile, the largest online jewelry seller, reported a year-on-year sales increase of 9.7% for the second quarter (ending July 4) but has noted slower third-quarter sales (not yet announced).
The world’s two fastest-growing economies, China and India, are also increasingly important diamond markets. Both are on target for economic growth of about 10% this year, according to an International Monetary Fund (IMF) report.
The IMF’s latest World Economic Report says the Chinese economy will grow 10.5% in 2010 and 9.6% in 2011, driven by domestic demand. India’s gross domestic product will expand 9.7% in 2010 and 8.4% in 2011, as a result of strong industrial production.

The IMF noted that mature Western economies, continuing their slow recovery from the economic downturn, are forecast to grow 2.7% this year and 2.2% in 2011.

Sapphire Mining Update – Southern Madagascar

We publish courtesy of G&G eBrief

Author: Vincent Pardieu, GIA Laboratory, Bangkok

Photos by Vincent Pardieu

In July-August 2010, this contributor visited the Ilakaka-Sakaraha and Andranondambo mining areas in southern Madagascar with several colleagues. In addition to collecting reference samples for GIA, our goal was to assess the state of the sapphire industry in the region.

Discovered in 1998, the Ilakaka-Sakaraha deposit extends more than 80 km from the Isalo National Park toward Toliara on the southwest coast. The area produces an abundance of pink and blue sapphires (most of which require heat treatment), as well as a wide variety of other gems.

Many Thai and Sri Lankan dealers have buying offices in the area, and most of the stones are exported to those two countries for heat treatment and cutting. Compared to my previous visits in 2005 and 2008, the number of foreign buyers has dropped, and they are paying lower prices for the gems.

Mining activity has also waned; we found only three small operations (two Thai, one Malagasy) still using machinery. The main mining area was located near Antsoa, southeast of Sakaraha, where about 1,500 miners were active. Antsoa was reportedly producing the best blue sapphires, with fine rough stones up to 10 g.

We found anywhere from 10 to 500 people working at the more than 20 other sites we visited. We estimate that about 50,000 people are now earning a living (directly or indirectly) from sapphire mining in Ilakaka-Sakaraha, half the number reported in 2005.

In the Andranondambo area, blue sapphires are mined from several primary deposits by small groups of artisanal miners near Andranondambo, Maromby, Tirimena, and Siva. The most active mining area appeared to be Ankazoabo (north of Andranondambo), where Malaysian company Nantin Ltd. was operating heavy machinery alongside some 200 artisanal miners using hand tools.

Gem mining in Madagascar, particularly in Ilakaka, has faced many difficulties in recent years. In particular, from February 2008 to July 2009, the Malagasy government banned all gem exports. The main reason for the current decrease in activity seems to be the global economic crisis and the resulting poor market. In turn, the mining community has suffered shortages of food and other necessities, and security issues plague the region. Shrinking margins have led to fierce competition between buyers, and many are considering a switch to ruby dealing in Mozambique.

Industry Analysis: High Demand, Hard Bargaining at Hong Kong Show

We publish courtesy of GIA’s Gems & Gemology EBrief

Author: Russell Shor

The Hong Kong Jewellery and Gem Fair opened Sept. 14 with heavy traffic, high expectations and hard bargaining on prices.

Although China is the world’s fastest-growing market and largely unaffected by the world economic slump, buyers were cautious about prices, especially in the diamond pavilion, where considerable down-trading was evident.

Exhibitors at the Asia World Expo Center near the airport reported that demand was fairly strong for diamonds, but that buyers were looking mainly for middle- and lower-clarity goods — a clear break from the past, when they would rarely buy grades below VS1.

Even the rarefied world of top fancy-colored diamonds witnessed a cautious approach, as exhibitors reported that buyers have been bargaining hard on prices and then walking away (perhaps to return before the show ends).

“A lot of stones never make it to the (cutting) wheels today,” said one dealer. “This is the case with big stones and top qualities — D and E colors and high clarities — where prices may be better later on.”

Colored stones were also in demand, but again dealers reported that truly top goods were extremely hard to find because of a prevailing belief that prices will improve.

After several well-publicized thefts during the first day of the show — including a large diamond and an emerald necklace — organizers increased security, requiring buyers at the gemstone pavilion to provide a photo ID along with their show credentials.

Zimbabwe: In other news, Zimbabwe sold a second lot of diamonds from its controversial Marange deposit this week. Details about the prices paid or the quality of diamonds in the sale were not released by Insider press time. This sale follows the 900,000 carats sold at the August tender, which reportedly brought some $43 million.

The rough diamonds had been embargoed until last month, when Kimberley Process officials who investigated conditions at the four Marange mining areas issued a decision that KP requirements were being met.

Most of the buyers at the September sale were diamond manufacturers from India and rough brokers from Dubai.

An estimated four million carats are stockpiled at Marange, and new production could total several million carats a year.

Russell Shor, Senior Industry Analyst

Intense Purplish Pink Synthetic Diamond, HPHT Grown and Treated

We publish courtesy of GIA’s Gems & Gemology G&G eBrief

Author: Paul Johnson, GIA Laboratory, New York

This 0.20 ct Fancy Intense purplish pink round brilliant proved to be a treated synthetic diamond. Photo by Jian Xin (Jae) Liao.

Many pink-to-red diamonds in the jewelry market owe their color to the natural material being treated with multiple processes, such as high-pressure, high-temperature (HPHT) annealing combined with irradiation and annealing at relatively low temperatures. This technique has also been applied to HPHT-grown synthetic diamonds since the 1990s, and today it appears that some of these synthetics are intentionally produced with very low nitrogen concentrations for a more intense color appearance after post-growth treatment.

A 0.20 ct round brilliant submitted to the New York laboratory was Fancy Intense purplish pink and contained few inclusions. Our initial observations suggested it might be one of the multiple-treated natural diamonds described above. It displayed strong color zoning and fluoresced strong orangy red to both long- and short-wave UV radiation. Absorption spectroscopy showed it was type Ia with very low nitrogen; the pink color was produced by strong NV centers with zero-phonon-line absorptions at 575 and 637 nm. These centers can be produced by multiple treatments, and an additional strong peak at 595 nm was indicative of artificial irradiation. These features are very similar to those seen in multiple-treated natural diamonds.
Careful examination with the DTC DiamondView instrument, however, revealed a subtle multi-sectoral growth structure that proved it was an HPHT-grown synthetic diamond. It appears that this synthetic diamond was carefully grown with a very low concentration of nitrogen (approximately 1 ppma), but enough to induce the high concentration of NV centers responsible for the intense pink color during post-growth treatment.

Care is needed to separate these treated synthetic pink-to-red diamonds from treated natural diamonds.

G&G: Tanzanite, other gems set with colored glue

A colored adhesive is present on the crown facets of this 1.87-carat tanzanite, shown here magnified 20 times. Photomicrograph by Nathan Renfro, (c) Gemological Institute of America (GIA). Reprinted by permission.

We publish courtesy of GIA‘s G&G

Carlsbad, Calif—The latest edition of G&G’s eBriefcontains several items of interest to those on the lookout for colored gemstone treatments: One is the discovery of tanzanite and other gems set with colored adhesive to darken their color, and another is the revelation that a ruby set in a piece of antique jewelry was actually filled with lead glass, a relatively new treatment.

The news was included in a G&G eBrief newsletter sent out Aug. 3 by Gems & Gemology, a Gemological Institute of America publication devoted to the latest gemological research.

The adhesive-set stones were discovered by a California goldsmith who was removing stones from some bezel-set rings that he had purchased in 2009 from a customer who had bought the rings from a TV home shopping network. He noticed that the tanzanite and other gems were set with what appeared to be colored adhesive, and alerted the GIA in March 2010.

Upon inspecting a 1.87-carat tanzanite submitted by the goldsmith, the GIA laboratory team found that a purple-colored flexible adhesive was visible on some of the crown facets, particularly at the corners. After it was removed, the color of the tanzanite appeared “very slightly lighter,” the eBrief said. The goldsmith told GIA that the other stones he removed from the rings became noticeably lighter once the adhesive was removed and that was particularly true for the amethyst.

“The colored adhesive was obviously intended to enhance the appearance of the stones, as well as help hold them in their mountings,” says the G & G eBrief item from GIA. “Buyer beware!”

The second colored stone treatment related item stemmed from a report from the American Gemological Laboratories (AGL), which uses the term “composite ruby” to distinguish lead glass-filled rubies from rubies that undergo the more common heat treatment. The former have drawn a lot of attention within the gemstone trade because they require special care during repairs and can also be damaged by common household chemicals.

The AGL item noted that despite the prevalence of the composite rubies in the marketplace, the lab was surprised to find such a ruby in an antique pendant submitted for identification. The pendant, which did not appear to be a replica, was set with old-mine-cut diamonds and seed pearls, consistent with its apparent age, but the lab identified the center stone as a composite ruby, with an estimated weight of 7.5 carats. The composite ruby had been carefully reset (the milgrain around the bezel was in good condition), and the lab detected no degradation of the glass in the stone—something that could be caused by the jeweler’s torch.

“The fact that this material has started to show up in antique jewelry is representative of how far it has penetrated the market and reinforces the importance of proper identification and disclosure,” the author of the eBrief item, from a staffer at the AGL laboratory, wrote.