Diamond Shapes and the Impact of Rough Recovery on Pricing

 

Insights from the Diamond Certification Laboratory of Australia (DCLA)

In the diamond industry, shape is far more than an aesthetic choice. It plays a direct role in value, pricing structure, and how efficiently a rough diamond can be transformed into a polished stone. At the Diamond Certification Laboratory of Australia Diamond Certification Laboratory of Australia (DCLA), one of the key considerations in diamond assessment is how much of the original rough crystal is recovered during polishing.

This recovery rate, often referred to as yield, is one of the hidden drivers behind diamond pricing and helps explain why different shapes are priced differently in the wholesale and retail markets.

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Understanding Rough Diamond Recovery

When a rough diamond is cut and polished, a significant portion of the original crystal is lost. This loss is unavoidable due to the need to remove inclusions, shape the stone, and maximise brilliance.

Different shapes produce different recovery percentages:

• Higher yield shapes retain more of the original rough
• Lower yield shapes sacrifice more material to achieve optical performance and symmetry

This difference directly impacts cost efficiency for cutters and ultimately influences market pricing.

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Round Brilliant Cut: The Lowest Yield but Highest Demand

The round brilliant cut remains the most popular diamond shape globally due to its unmatched brilliance and light performance. However, it also has the lowest average recovery rate, typically ranging from 40 percent to 45 percent of the original rough diamond.

This means that more than half of the rough stone is lost during cutting. As a result, cutters must allocate more rough carat weight to produce a finished round brilliant diamond.

Because of this inefficiency, round diamonds carry a distinct pricing structure. They are often listed on a separate price sheet compared to fancy shapes, reflecting their lower yield and consistently strong market demand.

In practice, this means:

• Higher cost per polished carat
• Separate pricing benchmarks in global diamond trading
• Strong liquidity due to consumer preference

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Fancy Shapes and Higher Recovery Efficiency

Fancy shaped diamonds generally achieve higher recovery rates, often between 50 percent and 70 percent depending on the specific shape and quality of the rough stone.

Common fancy shapes include:

• Oval
• Cushion
• Princess
• Emerald
• Pear
• Marquise
• Radiant
• Asscher

These shapes allow cutters to follow the natural structure of the rough diamond more efficiently, reducing waste and improving yield.

Because more of the rough diamond is preserved, fancy shapes are generally more cost efficient to produce. This efficiency is reflected in their pricing, which is typically lower per carat compared to round brilliant diamonds of equivalent quality.

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Why Shape Drives Price Differences

The difference in pricing between round and fancy shapes is not simply a matter of popularity. It is fundamentally linked to manufacturing economics.

Key factors include:

1. Rough Utilisation

Round diamonds require significantly more rough material per finished carat, increasing production cost.

2. Cutting Strategy

Fancy shapes are often designed to maximise retention of weight from irregular rough crystals, improving overall yield.

3. Market Demand

Round brilliant diamonds remain the most in demand, which further strengthens their premium pricing structure.

4. Inventory and Supply Chain

Because fewer polished carats are produced from the same amount of rough, round diamonds are less efficient to supply, reinforcing their separate pricing benchmarks.

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Separate Pricing Structure for Round Brilliant Diamonds

Due to their unique combination of high demand and low recovery efficiency, round brilliant diamonds are typically priced using a dedicated pricing list in the wholesale market.

This separation reflects:

• Higher manufacturing loss during cutting
• Consistent global demand for round brilliance
• Different valuation dynamics compared to fancy shapes

Fancy shapes, by contrast, are generally grouped within broader pricing frameworks that account for their higher yield and more flexible cutting outcomes.

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Diamond shape is not only a design choice but a critical economic factor in the diamond industry. Recovery rates from rough stone directly influence pricing structures, with round brilliant diamonds standing apart due to their lower yield and strong consumer demand.

At DCLA, understanding these differences is essential for accurate valuation, certification, and market analysis. As the diamond trade continues to evolve, the relationship between rough recovery and polished pricing remains one of the most important principles shaping global diamond values.

Source: DCLA

South Africa's New Guidelines to Boost Domestic Polishing

 

South Africa has introduced new guidelines to retain more economic value from its rough diamonds by promoting local cutting and polishing, rather than exporting goods unprocessed.

Around 90% of its rough diamond production is currently sold abroad. The South African Diamond and Precious Metals Regulator (SADPMR) is tackling this by requiring genuine offers of certain rough to local buyers first – at reasonable prices and practical assortments.

Producers are currently required to allocate 10% of run-of-mine (ROM) rough -total unsorted output straight from the mine – to the State Diamond Trader (SDT), a government entity that resells it to local beneficiators (licensed cutters and polishers).​

The remaining 90% (known as non-SDT rough) has, until now, been exported by sellers who have deliberately deterred local buyers with high prices and poor bundles, favoring tenders in Antwerp and Dubai.​

SADPMR now mandates that they make genuine rather than sham offers to sell this non-SDT rough to domestic cutters and polishers.

It must be displayed for at least four days at the Diamond Exchange and Export Centre (DEEC) in Johannesburg before export approval. There is no quota change, just stricter enforcement to boost local uptake.

Souurce: DCLA

Global Diamond Industry Shows Signs of Recovery: What Is Driving the Rebound?

 

After three challenging years marked by geopolitical disruption, shifting trade routes, and weakened consumer confidence, the global diamond industry is beginning to stabilise and recover. While price volatility persists in certain segments, demand is gradually rebuilding, particularly across the world’s primary luxury markets. Industry professionals broadly agree that the recovery remains uneven, but the direction is clear: a slow yet meaningful turnaround is underway.

Senior figures within the international jewellery trade point to improving economic sentiment as a key catalyst behind renewed interest in diamonds. Changing consumer behaviour is also playing a central role. Natural diamonds continue to dominate global engagement ring sales, retaining their status as the benchmark for long-term value and emotional significance. However, competition from lab-grown diamonds is intensifying, and the market share gap is narrowing.

In major Western markets, lab-grown diamonds are gaining traction, particularly among younger buyers who place greater emphasis on size, clarity, and price accessibility than on tradition. This generational shift is reshaping purchasing decisions and influencing how value is assessed at the point of sale.

Pricing dynamics underscore this transformation. Over the past year, prices for smaller natural diamondsespecially those under one carat have experienced notable declines. At the same time, lab-grown diamond prices have fallen even further, driven by rapid technological advancements and expanding production capacity. Together, these opposing movements have redefined the competitive landscape, prompting consumers to compare value propositions more closely than ever before.

While challenges remain, the combination of stabilising demand, evolving consumer preferences, and market-driven price realignment suggests the diamond industry has entered the early stages of recovery, with long-term implications for both natural and lab-grown sectors.

Source: DCLA

Second Biggest Diamond in Brazil’s History

A 647-carat diamond recovered in Brazil is the country’s second biggest and has been valued at just over $3m.

The brown-colored gem was unearthed late last month in the Douradinho river bed, home to mining companies and artisanal miners (known locally as garimpeiros) in the rural area of Coromandel, in the southeast of the country.

Large diamond finds are rare in modern Brazil and generate significant local excitement and economic activity, especially in towns with a mining tradition like Coromandel.

“Everyone was euphoric because Coromandel has a lot of mining activity,” said a spokesman for the Coromandel municipality. “It has been a long time since a diamond of this size was discovered.”

The record for Brazil’s largest diamond is still held by the 726.6-carat President Vargas diamond, discovered in the same region back in 1938.

Brazil was the world’s top producer of diamonds from 1730 to 1870, but is now responsible for less than 1 per cent of global production, mostly from alluvial deposits.

According to the Brazilian news website Click Petroleo e Gas, the gem has already been sold.

Source: DCLA

Karelian clears key hurdle for EU’s first diamond mine

Karelian Diamond Resources has registered its Lahtojoki mining concession in the Finnish land registry, advancing its plan to develop what could become the European Union’s first diamond mine.

This registration, handled by the Finnish mining authority TUKES, allows the company to proceed with further development plans for the Lahtojoki diamond deposit.

TUKES had previously approved the concession and is also responsible for issuing the mining certificate.

Karelian noted that a hearing on compensation matters related to the project has been postponed until the Fall of 2025, potentially impacting the timeline for full-scale operations.

Lahtojoki is known for its high-quality gem diamonds, including rare pink and coloured stones that can fetch up to 20 times more than typical colourless gems. The company believes the diamondiferous kimberlite pipe has the potential to support a profitable, low strip ratio open-pit operation.

The Dublin-based company is simultaneously exploring and advancing other assets in Finland, containing nickel, copper and platinum group elements. It is also advancing exploration at a site in the Kuhmo region where it aims to discover the source of a rare green diamond it found in 2022.

Source: Mining.com

Petra Diamonds rethinks sales tactics as market slump drags on

Africa-focused Petra Diamonds has scrapped regular diamond tenders in favour of opportunistic sales as the market for rough stones continues to slump.

The miner reported $53 million in sales from its fifth and sixth tenders of the year, covering production from its two South African mines. Petra will now report sales on a quarterly basis instead of following a fixed tender schedule.

“In response to fluctuations in diamond prices and demand, the company no longer follows regular tender cycles and may postpone portions of tenders or sell goods as run-of-mine,” the company said.

The strategic pivot mirrors De Beers’ reported off-market sales of discounted diamonds to selected clients. The move aimed to reduce inventory without officially slashing prices.

Petra said it sold 613,747 carats in the two tenders, a 29% increase from its fourth tender in February. The average price was $86 per carat, about 4% higher than February’s auction. On a like-for-like basis, prices were down 16% compared to the first six tenders of 2024, largely due to lower-value goods.

Year-to-date, the company has sold 2.39 million carats for $239 million, down from $329 million over the six first tenders of its 2024 financial year.

Petra delayed its April and May tenders due to a weaker product mix at its flagship Cullinan mine. The Finsch mine, meanwhile, saw improved pricing thanks to better ore access. The company expects an improved product mix as it ramps up production from the CC1E and the western side of the C-Cut block.

Petra also drew an additional $33 million in debt, bringing its consolidated net debt to $258 million by the end of March. It attributed this to working capital requirements.

“The continuing challenges in the diamond market and the weaker sales do not bode well given the ongoing negotiations to refinance Petra’s debt obligations,” Raj Ray, an analyst at BMO Capital Markets, wrote on Monday.

Petra has been restructuring to cut costs, including the sale of its stake in Koffiefontein in October and the recent $16 million sale of the Williamson mine in Tanzania.

Petra shares fell almost 3.5% on the news to 19.5 pence each, putting its market cap at about £38 million ($51 million).

Source: DCLA

HB Antwerp to Cut Lucara’s 1,094 carat Rough Diamond

The 1,094-carat Seriti diamond recovered last September from Lucara’s Karowe mine, in Botswana, is now in Belgium, where it will be cut by HB Antwerp as part of an ongoing partnership.

HB, founded in 2020, cut the 1,758-carat Sewelo diamond and the 549-carat Sethunya diamond – both of which were recovered at Karowe and both of which were bought by Louis Vuitton.

Exact prices were not disclosed, although Lucara did say last month that the Sethunya and the 1,080 carat Eva Star, sold for a combined $54m. HB gave no details of a buyer for the Seriti.

Seriti is the world’s sixth largest rough diamond, and the sixth +1,000-ct diamond recovered at Karowe.

HB says it will use “groundbreaking technology, traceability, and expertise to unlock the full brilliance of nature’s most exceptional creations”.

That includes its proprietary Hyperloupe technologies, designed specifically for large (up to 6,000 carats) and complex diamonds.

HB has a 10-year contract with Lucara to cut all its +10.8-cts stones. They account for around 70 per cent of the miner’s revenue.

Source: Idex

US$15 million in diamonds stolen in Namdia heist

A brazen diamond robbery at Namibia Desert Diamonds (Namdia) early on Saturday evening and involving what is suspected to be the company’s largest-ever consignment of precious stones received, has resulted in two fatalities and two arrests.

Although the figure could not be independently verified, a person with intricate knowledge of the matter said the diamonds are worth more than US$15 million (about N$280 million).

This consignment was reportedly delivered to Namdia’s premises by the Namibia Diamond Trading Company (NDTC).  NDTC is a 50:50 joint venture between the government and De Beers Namibia Holdings. It was formally conceived in January 2007 following an agreement to sort, value and market Namibian diamonds.

Responding to questions yesterday, NDTC CEO Brent Eiseb could not provide any details for security reasons. 

“For safety and security reasons, NDTC does not provide details of rough diamond deliveries/movements. Kindly refer all incident-related queries to Namdia,” Eiseb said.

The Namibian Police have said the exact amount of diamonds stolen in the robbery is unknown, pending an inventory by Namdia.

“The suspects fled with an unspecified amount of Namdia’s diamonds, whose value
is still to be ascertained. There were four suspects involved in the robbery. Two suspects are currently on the run. One suspect is in police custody. One suspect died from a self-inflicted gunshot wound during the incident,” Alisa Amupolo said in another statement issued late yesterday. According to sources familiar with Namdia’s modus operandi, the company was warned to tighten up its security. 

This, however, never happened.  “There were several warnings last year that the security left a lot to be desired. The staff has been worried about this.  The board chairman [Justus Hausiku] warned Alisa Amupolo [CEO] several times to focus on security,” said the source, who preferred to speak on condition of anonymity. 

Despite the advice to improve its security, Namdia’s offices were guarded by a single security guard only identified as Herman, who was seconded from a local security company. 

During the heist, Herman was handcuffed, but somehow managed to notify people at neighbouring premises to call the police, claiming “we’re being robbed”.

Execution

The police confirmed the execution-style killing of a Namdia protection officer during the robbery, as well as one of six perpetrators who succumbed to injuries sustained during the theft. “It is with deep sadness that we confirm an attempted armed robbery at our premises earlier today [Saturday], which tragically resulted in the loss of one of our valued staff members. We are cooperating fully with law-enforcement, and a thorough investigation is currently underway. As this is an ongoing investigation, we are working closely with the relevant authorities to establish the facts surrounding the incident. Namdia remains fully committed to ensuring the safety and security of both its staff and diamonds,” Amupolo said.

Crime report

The weekend police crime report issued yesterday stated that the robbery and murder occurred between 17h00 and 18h00 at the Namdia head office in Klein Windhoek. The police say armed suspects broke into the Namdia premises through yet-to-be determined means. 

The police further said the robbers held staff hostage by tying them up before stealing an undisclosed amount of diamonds.

“In one of the storerooms, the supervisor, who is a protection officer, was found dead with his hands and legs tied up and his face covered with a shopping bag, and a gunshot wound inflicted to the head. He was identified as Francis Eiseb, a 57-year-old Namibian male. His next of kin have been informed of his death,” the police crime report states.

Police said one of the robbery suspects was found with what appeared to be two gunshot wounds.  Late yesterday, police identified Max Endjala as the deceased suspect who was allegedly involved in the Namdia heist. His next of kin have also been informed of his death. He was an auditor at a local firm, according to reports. 

Law-enforcement officers at the scene collected four firearms and some knives. The investigation is ongoing, with the police appealing to members of the public who might have any information about the robbery or the suspects to pass it on to the relevant authorities.

Furthermore, sources said staff at Namdia were called in yesterday for interrogation on the robbery, which some people suspect took place based on inside information regarding the amount of diamonds on the premises at the time.

Family ties 

State broadcaster NBC also reported that one more arrest had been made in connection with the robbery. The male suspect is employed as a security officer at Namdia and is related to Endjala, the suspect who allegedly shot himself in the head, NBC reported.

Fond memories

In a social media post on Sunday, Namdia’s former CEO Kennedy Hamutenya hailed Eiseb as one of the hardest-working and most committed employees during his time. 

Eiseb, he reminisced, would perform above and beyond the call of duty. “He’d even volunteer to drive clients to and from the airport to ensure their safety. He was kind and cordial to all other colleagues, and was full of respect,” Hamutenya’s post reads.

Also taking to his WhatsApp social media platform yesterday was Bryan Eiseb, the Head of the Financial Intelligence Centre and a brother of the late Francis, who said the Eiseb family has “forgiven those who are responsible for Francis’ horrendous death. You [Francis] have paid the ultimate price for Namibia.” 

Namdia was founded by the government in 2016 to independently market and sell Namibia’s diamonds on the international market.  The Namdia headquarters is considered one of the most secure in Windhoek, considering the value consignments it regularly handles. It is estimated that Namdia annually sells some N$2 billion worth of diamonds on the international market. 
Read more: ‘N$280m gems’ stolen in Namdia heist  https://neweralive.na/n280m-gems-stolen-in-namdia-heist

Source: DCLA

KP Votes to End Ban on CAR Diamonds

The Kimberley Process voted to allow rough diamond exports from the Central African Republic (CAR) after imposing a ban in 2013 as a civil war raged.

The Seleka, a coalition of predominantly Muslim rebel groups, toppled the government in a conflict, reportedly funded by conflict diamonds, that saw widespread killings, rapes, and destruction of villages.

The country – one of the world’s poorest – still faces significant challenges in establishing lasting peace and stability, although the government and its Russian mercenary allies have since pushed rebel groups out of major towns.

The KP, at its plenary in the UAE last Friday (15 November), voted to re-admit CAR as a full member, in light of what it described as “an improving security situation”.

Diamond exports have, until now, been outlawed from the so-called red zones – representing two thirds of his country’s diamond mining areas. They will now be allowed. 

Legal exports, from CAR’s green zones, totaled just under $8m in 2020, the latest year for which KP has figures – 50,433 carats for an average $142 per carat.

Rufin Benam-Beltoungou, CAR’s minister of mines and geology spoke of his “joy and satisfaction” over the full lifting of the rough export ban.

UAE’s Kimberley Process chair, Ahmed Bin Sulayem, travelled to CAR and had pushed extensively for the KP to initiate a review mission to fast-track the country’s reintegration.

Source: DCLA

PS: Plain to see that the Kimberley Process is a political tool and not a safegaurd for the diamond industry.

India’s Polished Exports Fall Again in August

Diamond polisher in a factory

India’s exports of polished diamonds fell by 23.8 per cent year-on-year in August, according to the latest figures from the GJEPC (Gem and Jewellery Export Promotion Council). 

Total foreign sales were $1.04bn, compared to $1.36bn last August. Exports in July were $908m, down 22.7 per cent.

Polished diamond exports have fallen every month this year, down 20 per cent in January, 28 per cent in February, 27 per cent in March, 17 per cent in April, 15 per cent in May and 26 per cent in June. All figures are for US dollars.

Gross exports of all gems and jewelry fell by 18.8 per cent during August – a slower rate of decline than diamonds – to $2.01bn.

Rough imports for the April to August period were down 22.6 per cent to $4.98bn.

Source: DCLA

Huge Budget Boost for India’s Diamond Industry

India’s diamond industry welcomed a raft of measures announced in today’s budget (23 July) which will encourage direct diamond sales from foreign mining companies and reduce tax on key raw materials.

Finance Minister Nirmala (pictured) said safe harbor rates would be introduced, providing fixed and favorable tax rates for rough purchases in the country’s SNZs (Special Notified Zones).

Safe harbor streamlines the taxation process and eliminates unexpected liabilities for foreign suppliers.

Sitharaman also announced significant tax reductions on gold and silver to 6 per cent (from 15 per cent and 10 per cent) and on platinum to 6.4 per cent (from 12.5 per cent) and the exemption of diamond sales from a 2 per cent equalization levy aimed at promoting sustainability.

“India is a world leader in the diamond cutting and polishing industry, which employs a large number of skilled workers,” Sitharaman said in her Budget speech.

“To further promote the development of this sector, we would provide for safe harbor rates for foreign mining companies selling raw diamonds in the country.”

“I want to applaud and congratulate the Central Government for their three-point game changing decisions for the gems and jewellery industry,” said Vipul Shah, chairman of GJEPC (Gem and Jewellery Export Promotion Council).

“The reduction of customs duty on gold and silver, exclusion of diamond sector from 2 per cent equalisation level and simplifying taxation rules in Special Notified Zones (SNZ) for rough diamonds will provide a leadership position to the Indian gems and jewellery industry.”

Source: DCLA

Gahcho Kué diamond mine surpasses spend threshold with NWT and Indigenous businesses

Naturally fluorescing rough diamond parcel from the Gahcho Kué mine. Credit: Mountain Province Diamonds

De Beers Group and Mountain Province Diamonds announced that their joint venture Gahcho Kué diamond mine has surpassed the C$2 billion spending threshold with Northwest Territories and Indigenous business.

The milestone represents 61% of the total C$3.2 billion spent on the project since 2015 when construction began. Local businesses supply welding, transportation logistics, trucking, passenger and cargo flights, labour, and camp catering. The venture has a stated goal of sourcing at least 60% of its requirements for the project from local businesses.

According to the NWT Bureau of Statistics, diamond mining is the largest contributor to the territory’s gross domestic product – C$588 million out of C$4.25 billion in 2023.

Key elements of the economic contribution of the Gahcho Kué mine include:

Gahcho Kué has a tiered contracting structure that gives preference to Indigenous and NWT businesses.
Since 2006, C$5.3 billion has been spent with local and Indigenous business in the Northwest Territories and northern Ontario by Gahcho Kué and De Beers Group’s wholly owned Snap Lake (NWT) and Victor (Ontario) mines. (Snap Lake and Victor are now in active closure).
In 2023, 69% of the Gahcho Kué mine spend was with NWT and Indigenous companies, totalling C$228 million, the highest amount spent with NWT businesses since construction.
In 2023, C$90 million was spent with companies operated by the mine’s impact benefit agreement (IBA) communities.
From 2006 to 2023, Gahcho Kué and Snap Lake mines have contributed a combined C$26.5 million in social investment within the NWT.
Gahcho Kué has also made significant payments to Indigenous communities in terms of six IBAs and has paid resource royalties to the government of the NWT.
Gahcho Kué was officially opened in 2016 and now provides 663 full-time equivalent jobs, including 245 jobs held by NWT residents.

The mine is located about 280 km northeast of Yellowknife, NWT, on the traditional territories of Tlicho, Dene and Metis peoples. De Beers is the 51% owner and operator. Mountain Province retains the remaining 49%.

In 2023 the project mined 3.3 million tonnes of kimberlite and recovered nearly 5.6 million carats (on a 100% basis). Guidance for 2024 is 4.2 million to 4.7 million carats.

Source: DCLA

Another Month of Decline for India’s Diamond Exports

A diamond in a polishing factory

India’s exports of polished diamonds suffered a further drop in May, down by almost 15 per cent to $1.47bn.

But the year-on-year rate of decline shows some signs of slowing, according to new figures from the GJEPC (Gem and Jewellery Export Promotion Council).

It fell 20 per cent in January, 28 per cent in February, 27 per cent in March and 17 per cent in April.

Diamonds are faring significantly less well than India’s overall gems and jewelry sector, which saw revenue for April slip by 6 per cent to $2.48bn.

Manufacturers bought more diamonds year-on-year in April and May (up almost 2 per cent by volume) but the price slump means imports are down almost 10 per cent by value are down by almost 10 per cent to $2.39bn.

Source: DCLA

Lucapa sells three diamonds for $10.5m in first tender

 Lucapa sells three diamonds for $10.5m in first tender

A 203 ct Type IIa diamond as part of Lucapa’s first Lulo tender of the year

Lucapa Diamond Company has sold three exceptional diamonds recovered from the Lulo mine, in Angola, for $10.5-million at tender.

The tender was concluded on April 19 and was conducted by Sodiam, in Luanda.

The three Type IIa white diamonds, weighing 203 ct, 116 ct and 43 ct, made up Lucapa’s first tender of Lulo diamonds for this year.

The total parcel, weighing 361 ct, realised an average price of $29 000/ct.

Lucapa has a 40% interest in the Lulo alluvial mine, alongside Angola’s national diamond company Endiama and a private entity called Rosas & Petalas.

Source: DCLA

US Sanctions Zimbabwe President for Diamond Smuggling

The US has sanctioned Zimbabwe President Emmerson Mnangagwa for corruption in connection with gold and diamond smuggling, as well as human-rights abuses.

The Treasury Department’s Office of Foreign Assets Control (OFAC) accused Mnangagwa of “providing a protective shield” to gold- and diamond-smuggling networks that operate in Zimbabwe, it said last week. He is also accused of directing Zimbabwean officials to “facilitate the sale of gold and diamonds in illicit markets” and taking “bribes in exchange for his services.”

The US has also restricted Mnangagwa for being a leader or official of entity, including any government entity, that has “engaged in, or whose members have engaged in, serious human-rights abuses,” OFAC explained.

“The Zimbabwe president is a foreign person who is a current or former government official, or a person acting for or on behalf of such an official, who is responsible for or complicit in, or has directly or indirectly engaged in, corruption, including the misappropriation of state assets, the expropriation of private assets for personal gain, corruption related to government contracts or the extraction of natural resources, or bribery,” OFAC stated.

OFAC issued the new sanctions after US President Joe Biden signed an executive order that terminated Zimbabwe’s national emergency and revoked sanctions on the entire country, so as not to target its citizens.

“The US remains deeply concerned about democratic backsliding, human-rights abuses, and government corruption in Zimbabwe,” said Wally Adeyemo, deputy secretary of the treasury. “The changes we are making today are intended to make clear what has always been true: Our sanctions are not intended to target the people of Zimbabwe. Today we are refocusing our sanctions on clear and specific targets.”

Source: DCLA

Lucara Diamond revives sales deal with gem trader HB Antwerp

Lucara Diamond has revived a gem sales agreement with polishing and trading company HB Antwerp, it said on Monday, five months after severing ties with the Belgian business.

Canadian miner Lucara said it will supply HB Antwerp with rough diamonds of 10.8 carats and above for 10 years from last December.

Lucara had terminated its relationship with HB Antwerp last September because of what it said was “a material breach of financial commitments”.

HB Antwerp declined to comment on the matter at the time and did not respond immediately to a request for comment on Monday.

Botswana, where Lucara mines diamonds at its Karowe project, has been reassessing plans to acquire 24% of HB Antwerp.

The two companies’ first diamond sales agreement was struck in 2020 and extended for 10 years in 2022.

Lucara said the purchase price for rough stones in its revised deal would be based on mutual agreement of the estimated value of polished diamonds, with a further payment based on actual achieved polished sales.

The pricing mechanism is expected to deliver regular cash flow, Lucara said.

“This partnership reflects our commitment to ensuring stability and sustainability in our operations,” said Lucara chief executive William Lamb.

Source: DCLA

New method could simplify detection of diamond deposits

Geologists from ETH Zurich and the University of Melbourne have established a link between diamond occurrence and the mineral olivine.

In a paper published in the journal Nature Communications, the scientists explain that their method will simplify the detection of diamond deposits. The process relies on the chemical composition of kimberlites, which occur only on very old continental blocks that have remained geologically unchanged for billions of years, predominantly in Canada, South America, central and southern Africa, Australia and Siberia.

According to the study’s lead author, Andrea Giuliani, olivine is a mineral that makes up around half of kimberlite rock and consists of varying proportions of magnesium and iron. The more iron olivine contains, the less magnesium it has and vice versa.

“In rock samples where the olivine was very rich in iron, there were no diamonds or only very few,” Giuliani, who has been studying the formation and occurrence of the gemstones since 2015, said in a media statement. “We started to collect more samples and data, and we always got the same result.”

His investigations ultimately confirmed that olivine’s iron-to-magnesium ratio is directly related to the diamond content of the kimberlite. Giuliani and his team took these findings back to De Beers, who had provided them with the kimberlite samples. The company was interested and provided the scientific study with financial support and asked the researchers not to publish the results for the time being.

A slow, repetitive process
In 2019, Giuliani moved from Melbourne to ETH Zurich and, supported by the Swiss National Science Foundation, began to look for explanations for the connection between olivine’s magnesium and iron content and the presence of diamonds.

With his new colleagues, he examined how the process of metasomatism, which takes place in the earth’s interior, affects diamonds. In metasomatism, hot liquids and melts attack the rock. The minerals present in the rock react with the substances dissolved in the fluids to form other minerals.

The geologists analyzed kimberlite samples that contained olivines with a high iron content—and hence no diamonds. They discovered that olivine becomes richer in iron in the places where melt penetrates the lithospheric mantle and changes the composition of mantle rocks significantly. And it is precisely in this layer, at a depth of around 150 kilometres, that diamonds are present.

The infiltration of the melt that makes olivine richer in iron destroys diamonds. If, on the other hand, no or only a small amount of melt from underlying layers penetrates the lithospheric mantle and thus no metasomatism takes place, the olivine contains more magnesium—and the diamonds are preserved.

“Our study shows that diamonds remain intact only when kimberlites entrain mantle fragments on their way up that haven’t extensively interacted with previous melt,” Giuliani said.

A key point is that kimberlites don’t normally reach the earth’s surface in one go. Rather, they begin to rise as a liquid mass, pick up fragments of the mantle on the way, cool down and then get stuck. In the next wave, more melt swells up from the depths, entrains components of the cooled mantle, rises higher, cools, and gets stuck. This process can happen multiple times.

“It’s a real stop-and-go process of melting, ascent and solidification. And that has a destructive effect on diamonds,” Giuliani noted. If, on the other hand, conditions prevail that allow kimberlites to rise directly to the surface, then this is ideal for the preservation of the gemstones.

De Beers is already using olivine analysis
Olivine analysis is as reliable as previous prospecting methods, which are mainly based on the minerals clinopyroxene and garnet. However, the new method is easier and faster: it takes only a few analyses to get an idea of whether a given kimberlite field has diamonds or not.

“The great thing about this new method is not only that it’s simpler, but also that it finally allows us to understand why the previous methods worked,” Giuliani said. “De Beers is already using this new method.”

Source: DCLA