A huge, one-of-a-kind “coin” created to mark Queen Elizabeth II’s Platinum Jubilee is to be auctioned with a high estimate of $4m.
The Crown Coin, commemorating her 70 years on the throne in 2022, was struck from 3.61 kg of 24-carat gold and set with 6,426 GIA-certified diamonds weighing a total of 483.57 carats. At 235mm across it is almost the size of a standard frisbee.
At the center is a 1kg gold coin – legal tender with a face value of £10,000 – surrounded by 10 smaller coins bearing official portraits from Queen Elizabeth II’s reign.
The “coin” was created by The East India Company Bullion Ltd, which makes commemorative and collectible bullion coins, and takes its name from the long-dissolved East India Company, which played a major role in establishing British imperialism in India.
Stanley Gibbons Baldwin’s, the London-based auction house specializing in coins and stamps, will offer it for sale on 25 September, with an estimate of £2m to £3m (USD 2.7m to 4.0m).
Rio Tinto is auctioning its final collection of rare diamonds from its closed Argyle mine in Australia and the soon-to-shutter Diavik operation in Canada.
The tender, called Beyond Rare, includes 52 lots totalling 45.44 carats and marks the end of an era for two of the world’s most celebrated diamond mines.
The centrepieces are six diamond sets selected to represent the peak of production from the East Kimberley region of Western Australia and the Northwest Territories of Canada. The tender also features 39 individual stones and seven curated sets.
Rio Tinto Diamonds’ general manager of sales and marketing, Patrick Coppens, called the auction a historic moment. “It is hard to overstate the importance of this final collection,” he said in the statement. “No other mining company in the world has custody of such an exquisite range of diamond colours, shapes and sizes.”
Rio Tinto closed Argyle in 2020, ending production of the famed pink, red and violet stones that made the mine world-renowned. Although Argyle accounted for about 75% of Rio’s diamond output, the impact on the company’s earnings was minimal, with diamonds contributing only about 2% of revenue. Diavik, the miner’s last diamond asset, is scheduled to close in 2026.
The collection includes one GIA Fancy Red diamond, 12 Fancy Violet, and 76 Fancy Pink and Purple-Pink stones from Argyle’s legacy inventory. From Diavik, highlights include two flawless D-colour white diamonds, an emerald cut weighing 5.11 carats and a pear shape of 3.02 carats. Both of them were cut from the same rough stone.
Collection includes one GIA Fancy Red diamond, 12 Fancy Violet, and 76 Fancy Pink and Purple-Pink stones from Argyle’s legacy inventory.
The tender also features a Fancy Vivid Yellow diamond weighing 6.12 carats.
The diamonds will tour Hong Kong, Australia and Antwerp before bids close on October 20. Industry insiders expect strong competition from top jewellers, collectors and connoisseurs.
The sale of diamonds through tenders and auctions is opaque and inefficient and should be revamped for producers to earn more and to survive the current price slump, a leading gem trader said on Thursday.
Oded Mansori, co-founder and managing partner of Belgian gem trader HB Antwerp, said the impact on producers could be reduced by doing away with inefficiencies in the industry.
The diamond market is currently going through a prolonged downturn with demand hurt by global economic uncertainty and the rising popularity of lab-grown stones.
Producer countries such as Botswana have been hard hit by lower revenues, while miners such Burgundy and Lesotho’s biggest diamond mine Letseng have had to lay off workers.
“For years, miners relied on tenders and auctions, systems that look efficient on paper but in practice resemble a casino,” Mansori said in a statement, as the industry battles a crisis considered to be its deepest in history.
“Rough stones are pushed into opaque markets where value is anyone’s guess. When global demand softens, as it has in cycles over the last decade, producers are left exposed. Workers pay the price, while shareholders watch assets decline,” he added.
Rough diamonds are typically sold through a competitive bidding system where buyers place confidential bids on individual stones or parcels.
Mansori, whose company operates a profit-sharing model with miner Lucara Diamond Corp, says producers’ revenues should be tied to the eventual polished value of its stones “rather than gambling on rough sales in opaque auctions”.
Under its partnership with Lucara, HB Antwerp buys stones of 10.8 carat quality and above from the Toronto-listed company’s Karowe Mine in central Botswana at prices based on the estimated polished value of each diamond.
HB Antwerp accounted for 72% of Lucara’s $74-million diamond revenue in the six months to June 30, up from 65% the year before.
The trader says producers can earn up to 40% more revenue if they sell through this model.
Rough diamonds that were locked in a 15-year legal dispute in Zimbabwe are finally being sold.
The UK miner Vast Resources is offering parcels totaling 135,000 carats at a series of public and private tenders from now until the end of October.
Vast surrendered the gems in 2010 amid allegations it had exploited diamonds on mining claims previously owned by De Beers, which withdrew from Marange in 2006, saying it had failed to find viable reserves.
Vast Resources (then known as African Consolidated Resources) subsequently discovered massive alluvial diamond deposits there, which prompted the Zimbabwe government to revoke its mining licenses within months, and evict it.
The diamonds, held at Zimbabwe’s central bank since 2009, were finally handed back to Vast in April of this year.
They have undergone an extensive cleaning process in Dubai to remove multiple layers of metallic silicates and mineral coatings. As a result, around 6,000 carats initially classified only as industrial diamonds have been upgraded to gem quality.
In an update (on 15 September) Vast spoke of “a unique opportunity to most effectively realize value from the long-awaited parcels from the historic settlement and could open further opportunities for the company in the future”.
Researchers at the University of Tokyo say they’ve found a way to make tiny diamonds without the need for high temperature or high pressure conditions – unlike current lab grown technology.
They use electron beams to break and remake bonds in adamantane (C10H16), a carbon molecule in which atoms are arranged in a pattern very similar to the atomic structure of diamond.
The process takes tens of seconds under transmission electron microscopy conditions in a vacuum (low-pressure chamber)
A team led by Professor Eiichi Nakamura, of the Department of Chemistry, has published its findings in the journal Science, in an article entitled Rapid, low-temperature nanodiamond formation by electron-beam activation of adamantane C-H bonds.
It explains how the controlled electron irradiation of adamantane produces defect-free nanodiamonds.
The breakthrough process is aimed at creating tiny diamonds for high-tech industries, scientific research, and medical fields, rather than larger gem-quality stones.
It works through gradual assembly of diamond lattice from adamantane molecules under prolonged electron irradiation, which naturally limits the size to nanodiamonds currently.
Larger diamond growth would require controlling fusion of these nanocrystals and sustained lattice perfection over much longer times and at a larger scale.
Gem quality lab growns are created either using High Pressure High Temperature (HPHT) or Chemical Vapor Deposition (CVD), which uses high temperatures and low pressure.
The World Jewellery Confederation (CIBJO) is set to reverse a decision made in 2010 – and insist that non-natural diamonds are labelled as “synthetic”.
It says the terms “laboratory-grown” and “laboratory-created” should be removed from the Diamond Blue Book – the de facto standard for diamond terminology, grading and trade practices – and from all relevant ISO Standards.
In addition, the 4Cs grading system should be used only for natural diamonds (as the GIA is now doing).
Udi Sheintal (pictured), president of CIBJO’s Diamond Commission, said the original acceptance of lab grown terminology had been well-intentioned, but proved to be misplaced.
“At the time, we believed we were acknowledging a commercial reality and extending a constructive hand to a new segment of the industry,” he said, in a special report ahead of the 2025 CIBJO Congress in Paris at the end of October.
“We hoped for a spirit of cooperation, with shared standards, ethics and transparency.”
But he said many in the synthetic diamond sector — along with some grading laboratories and major retail chains – took advantage of that inclusive approach.
“In addition, the marketing narrative around synthetic diamonds has been aggressively shaped to position them as the more ethical, sustainable, and conflict-free choice, almost always without substantiation.”
He also called for greater transparency, requiring that all descriptions and marketing of synthetic diamonds reflect the reality of their origin: they are not grown or created in a “laboratory,” but rather are manufactured in industrial facilities through artificial processes.
Patek Philippe will reportedly hike watch prices by 15 per cent tomorrow (Monday 15 September) in response to US reciprocal tariffs.
If confirmed, it will be Patek Philippe’s third price rise in the US this year, according to the WatchPro website.
Prices were increased in January because of soaring gold prices and the strength of the Swiss franc, and in April as a response to the US announcement of across-the-board tariffs.
Authorized dealers will also have their margins cut. Patek Philippe will be the first Swiss watchmaker to raise prices since the US introduced 39 per cent tariffs on 7 August.
Watchmakers rushed to export their goods ahead of the tariff deadline, resulting in a 6.9 per cent increase during July.
But price increases in the near future are almost inevitable as the reciprocal tariffs bite and stocks need replenishing.
One of the lowest-priced Patek Philippes, the $26,000 stainless steel Patek Philippe Aquanaut Ref. 5167A-001 (pictured) will cost $30,000 if the price increases take place.
Signet reported increased sales for Q2, as consumers increasingly opted for lab growns over natural diamonds.
It said 14 per cent of all the fashion jewelry items it sold during the quarter were lab grown – twice as many as the same period last year, and higher than Signet’s own expectations.
Total sales for the 13 weeks to 2 August were $1.5bn, up 3.0 per cent, and same store sales increased by 2.0 per cent, Signet said in its Second Quarter Fiscal 2026 Results.
Kay, Zales, and Jared the retailer’s three largest brands together delivered a combined 5 per cent same-store sales growth.
Adjusted operating profit for the quarter rose over 20 per cent reaching $85m, with a 24 per cent year-over-year gain.
Lab growns are viewed as a “category extender for fashion” and demand is most prominent in lower-priced products and fashion jewelry.
“Our second quarter results were driven by the expansion of on-trend fashion assortment and effective promotion and pricing strategies,” said J.K. Symancyk, Signet’s CEO.
Joan Hilson, chief operating and financial officer, said: “Reflecting second quarter results, expectations for the third quarter, and current tariff landscape, we’re raising our Fiscal 2026 guidance.
“This updated guidance also includes share repurchases to date and assumes a measured consumer environment.”
The modest increase largely reflects a rush by exporters to get their goods into the US before the tariff deadlines and retailers stockpiling for the same reason.
It offsets low consumer demand, which is being compounded by ongoing anxiety over US reciprocal tariffs which are expected to force up prices.
Average monthly growth in watch and jewelry sales so far, for the first seven months of this year, has been around 0.6 per cent, compared to over 5 per cent last year.
Sales in June were down 0.9 per cent, a figure that has been revised up from the original -1.7 per cent, based on actual transactions rather than estimates.
Exports of Swiss watches were up 6.9 per cent, largely driven by manufacturers front-loading their shipments to avoid 39 per cent US tariffs.
Recently, the Dubai laboratory encountered four stones submitted for update services inscribed with fraudulent GIA report numbers. Inconsistent font styles and placement indicated the numbers were not authentic GIA inscriptions.
Table 1. Comparison of characteristics of submissions with counterfeit inscriptions and their accompanying GIA grading reports. A careful comparison of their quality characteristics confirmed that these were not the same diamonds as described in their accompanying reports. Although the diamonds were carefully selected to closely match the features listed on the original reports, several subtle differences in their color grades, measurements, and other characteristics were identified (table 1). Even more obvious were the spectral differences between the fraudulent and original stones. The difference in the one-phonon region of the Fourier-transform infrared absorption spectroscopy clearly revealed a discrepancy in the diamond types. The diamonds from the original reports were type Ia with aggregated nitrogen impurities, while these submitted stones were all type IIa, confirming they were, in fact, different stones.
On fraudulent diamonds 1 and 2, photoluminescence (PL) spectra produced by 514 nm laser excitation at liquid-nitrogen temperature showed that 637 nm peaks were greater than 575 nm peaks. The 575 and 637 nm peaks are emissions from the nitrogen vacancy center in its neutral [NV]0 and negative [NV]− charge states, respectively. The 575:637 nm emission ratio of intensities of less than 1 (D. Fisher and R.A. Spits, “Spectroscopic evidence of GE POL HPHT-treated natural type IIa diamonds,” Spring 2000 G&G, pp. 42–49), along with other PL features, indicated that fraudulent diamonds 1 and 2 with the counterfeit inscriptions were natural diamonds that had undergone high-pressure, high-temperature (HPHT) treatment for color improvements.
The visible/near-infrared (Vis-NIR) absorption spectrum for fraudulent diamond 3, on the other hand, showed a 737 nm peak, which corresponds to the unresolved silicon vacancy [SiV]– defect at 736.6/736.9 nm commonly seen in laboratory-grown diamonds using the chemical vapor deposition (CVD) growth method (P. Martineau et al., “Identification of synthetic diamond grown using chemical vapor deposition (CVD),” Spring 2004 G&G, pp. 2–25). The observation of such features led to the determination that this stone was CVD-grown and subjected to post-grown HPHT processing.
Further PL spectroscopy analysis on fraudulent diamonds 3 and 4 using 633 nm excitation confirmed the presence of the SiV– doublet feature on both diamonds. In alignment with the Vis-NIR and PL spectra, DiamondView images of these two fraudulent stones displayed clear striations with interruption layers indicative of CVD growth (figure 1). These patterns are consistent with the step-flow growth structure of CVD-grown diamond, which was also visible under the microscope using crossed polarizers and further supported their laboratory-grown origins. The other two fraudulent diamonds (1 and 2), however, showed a lack of such patterns and demonstrated natural-looking features, which confirmed them as HPHT-processed natural diamonds.
Figure 2. GIA’s standard procedure is to cross out the counterfeit inscription. Image by GIA staff. Figure 2. GIA’s standard procedure is to cross out the counterfeit inscription. Image by GIA staff. Considering all evidence, we concluded that two of the four stones were laboratory-grown diamonds, and the other two were HPHT-processed natural diamonds. All four diamonds were not the same natural diamonds as described in their accompanying GIA grading reports. In accordance with GIA procedures, the counterfeit inscriptions were crossed out (figure 2) and new report numbers were assigned. In addition, GIA inscribes “TREATED COLOR” on natural diamonds with post-treatment history and “LABORATORY-GROWN” along with a GIA report number and distinct GIA LG logo on laboratory-grown diamonds.
Deceptive practices have occurred previously in the trade; similar instances of diamonds with fraudulent inscriptions have been reported by GIA (e.g., Summer 2021 Lab Notes, pp. 150–152; Fall 2021 Lab Notes, pp. 258–259). Additionally, non-diamond materials, such as synthetic moissanite, with fraudulent GIA inscriptions have been submitted as diamonds to GIA (Fall 2020 Lab Notes, pp. 424–425; Fall 2022 Lab Notes, pp. 360–361). These cases highlight the importance of verifying inscription authenticity because a fraudulent inscription could be overlooked by simple visual examination. One possible solution is GIA’s Match iD, a device that compares a diamond’s inscription with its grading report in the GIA database.
