How Rough Diamond Pricing Traps the Midstream in a Margin Squeeze

The businesses that cut and polish nearly every diamond you have ever seen sit trapped between two pricing systems they have almost no power to move. One system sets the price of the rough stones going in. The other sets the price of the polished stones coming out. Right now, both are moving against them at the same time.

For most people, the diamond market is a single moment: a price tag in a shop that reveals nothing about how the stone got there. The upstream reality is a controlled, largely opaque supply system, and understanding it, specifically who controls the rough stones, how they are sold, and where they physically move, is the only way to make sense of the stress now visible in the middle of the pipeline.

By the time you finish this, you will be able to trace the logic of pricing from the mine gate to the polished benchmark, and you will understand why the Rapaport price list is the one signal that traders and investors actually watch.

The sight system: how De Beers controls the first price in the chain

On the surface, the story is simple. De Beers sells rough diamonds. But the way it sells them reverses the normal relationship between a buyer and a seller, and that reversal is the foundation of everything downstream.

De Beers distributes rough stones through a structured sales calendar built around a small, vetted group of customers. The core mechanics look like this:

• Around ten sales events per year, known internally as sights
• A restricted group of roughly 80 approved buyers, called sightholders
• Pre-assembled parcels of rough diamonds, not individually selected stones
• Fixed prices set by De Beers, with no negotiation
• Strong pressure to accept the allocation, since refusing without justification risks a buyer’s standing in the system

A sightholder does not walk in, inspect the goods, and haggle. They are offered a box at a price, and they take it. That is not a market in the conventional sense. It is a controlled allocation, and it hands De Beers substantial influence over both the pace and the price at which rough diamonds enter the world.

The most important consequence for you to grasp is directional. Because acceptance is effectively expected, midstream buyers are structurally price-taking on their most important input. When the polished market weakens, they cannot simply demand cheaper rough. That is the first reason midstream margins are so difficult to defend.

When polished prices fall, miners cut volume, not prices

Here is the pattern that repeats. When demand softens, De Beers has historically preferred to reduce production targets or offer more flexible purchasing conditions rather than cut its headline rough prices. Trade coverage documented this during the post-2014 commodity slump, the 2015-2016 diamond downturn, and the COVID-era disruptions.

The strategy defends the price of rough. It also transfers the entire burden of adjustment onto the sightholders and the wider midstream, who are left holding high-cost inventory when polished realisations fall.

That the pressure became real is visible in the concessions. Trade outlets including Rapaport News and IDEX reported that across 2019-2023, De Beers allowed sightholders to defer or decline goods when rough looked too expensive relative to polished. Sightholders were increasingly unwilling to take loss-making boxes just to keep their status, a clear signal of strain in the traditional relationship.

Antwerp, Alrosa, and where rough diamonds actually change hands

Once rough leaves the primary producers, it needs somewhere to physically trade. That place, historically, has been Antwerp.

Antwerp, in Belgium, functions as the central physical marketplace where rough stones move between miners, dealers, and manufacturers. In a market otherwise built on closed, relationship-based systems like the sight, Antwerp offers a degree of open price transparency and liquidity. It is the clearinghouse that sits between the mine and the polishing floor.

For years, the sight system was not the only game feeding that floor. Alrosa, Russia’s largest producer and the world’s second major primary miner, ran a different model: competitive auctions combined with direct contracts with Indian manufacturers. Those auctions offered genuine, market-driven price discovery, and the direct contracts gave Indian polishers a supplementary source of rough entirely outside the De Beers framework. Two channels meant two sources of competitive pressure on price.

Then sanctions closed one of them. The timeline moved quickly:

1. In December 2023, the European Union agreed to ban the import, purchase, or transfer of Russian natural and synthetic diamonds.
2. The ban took effect on 1 January 2024, closing the EU market to Alrosa’s exports.
3. On 3 January 2024, following the bloc’s 12th sanctions package, the EU formally added Alrosa and its CEO, Pavel Marinychev, to the sanctions list.
4. Additional phases from March 2024 restricted stones mined in Russia but processed in third countries, shutting the loophole that had routed Russian rough through India into Western markets.

The European Commission sanctions FAQ on Russian diamonds sets out the phased implementation of Council Regulation 2023/2878, confirming that the March 2024 extension specifically closed the third-country processing loophole that had allowed Russian rough to enter Western markets via India.

The financial effect on Alrosa was severe.

Alrosa’s annual profit dropped 77% for the full year, according to Rapaport News (3 March 2025) and IDEX Online (4 March 2025), reflecting the cumulative weight of G7 and EU sanctions phased in from 1 January 2024.

With Western markets largely closed, Russia’s state repository, Gokhran, began buying part of Alrosa’s 2024 production, with the finance ministry confirming (via Reuters, 27-28 March 2024) that specific volumes would not be disclosed. Alrosa has published no detailed sales data since 2022.

The financial effect on Alrosa extended well beyond the initial sanctions wave; Alrosa’s deepening crisis, compounded by Russia’s own export duty regime layered on top of Western market closures, has reshaped the competitive dynamics that Indian polishers relied on for decades.

The two producers now look very different from the outside.

What this tells you is that the supply side is now more concentrated than it was before sanctions. Indian polishers who leaned on Alrosa’s auctions as a competitive alternative to De Beers boxes have lost bargaining leverage they will not easily recover, which helps explain why rough prices have not fallen proportionally even as polished prices collapsed. It is also worth noting that Antwerp itself has been losing rough trading share since roughly 2016, with volumes drifting toward Dubai, Mumbai, and Surat.

India’s polishing industry and why the margin squeeze is structural, not cyclical

India processes the majority of the world’s rough diamonds by volume, sourcing through both the sight system and direct producer contracts. That makes it the exact point where upstream and downstream pricing dynamics collide, and where the squeeze is most visible.

The compression is not the result of a single bad quarter. Four forces are working against Indian polishers at once:

• Miners’ production discipline, which holds rough prices firm even in weak demand
• Faster price transmission on polished than on rough, so polished falls quickly while rough lags
• Lab-grown diamond substitution, giving retailers a credible cheaper alternative
• Financing constraints, which tighten as polished prices fall but do not release sightholders from contractual expectations

Take each in turn. Miners defend rough by cutting volume, as covered above. Retailers, meanwhile, reprice polished almost immediately when consumer demand softens, so the spread that funds cutting and polishing gets squeezed from both directions. Lab-grown diamonds, now a commoditised lower-price option, let retail chains resist higher natural polished prices and swap in alternatives, particularly in the commercial qualities and smaller sizes that dominate Indian volumes. And when polished prices fall, financiers grow cautious, tightening credit while miners keep selling rough at stable prices.

Lab-grown diamond substitution has moved well beyond the premium novelty segment; in commercial qualities and smaller sizes that dominate Indian polishing volumes, lab-grown stones now give retail chains a credible, lower-cost swap that puts a structural ceiling on natural polished price recovery.

The numbers make the compression concrete. As of the November 2024 Rapaport release, the polished price index (RAPI) showed steep year-to-date losses across every size category, with only marginal monthly recoveries.

Source: Rapaport, 3 December 2024.

A polished price down more than 20% for the year while rough input costs hold firm tells you the spread funding the entire cutting-and-polishing business has been severely compressed. The tiny November recoveries in the smaller sizes are nowhere near enough to rebuild the margin structure that made Indian polishing viable at scale. When that spread vanishes, capacity adjusts fast: Surat has seen factory closures and reduced shifts in past downturns around 2012-2013, 2015-2016, and 2020-2021. Industry body GJEPC and bank risk reports across 2018-2023 also flagged rising compliance and KYC costs amplifying the financing pinch.

What the cyclical versus structural debate means in practice

So is this a rough patch or a permanent reset? The answer depends on who you ask.

Bain & Company reports and miner executives, including De Beers leadership under Bruce Cleaver and Al Cook, have argued the cyclical case: demand is tied to macro conditions and luxury sentiment, downturns clear once inventory normalises, and lab-grown will eventually settle into a separate lower-priced segment rather than displacing natural stones.

Martin Rapaport and the Rapaport Group, alongside many Indian manufacturers, take the structural view. They point to sustained divergence between rough and polished prices, concentrated miner power, and lab-grown commoditisation as evidence that the margin squeeze is lasting, not temporary.

A hybrid position splits the difference, and it is the most useful frame for you. Inventory overhang and near-term demand weakness are genuinely cyclical. But lab-grown commoditisation putting a ceiling on mainstream natural prices is a structural change that will keep midstream margins thin even in an upcycle.

The Rapaport price list as the market’s public signal

If the squeeze is the story, the Rapaport price list is how you measure it. And it is worth understanding exactly what it does and does not capture before you lean on it.

The Rapaport price list is the primary reference benchmark for polished diamond valuation. It standardises price reference points across grades and sizes, letting participants assess value and direction. It is not a live traded exchange price; it is a periodic assessment of market conditions. But it is the closest thing the downstream end of this market has to a publicly visible index.

Here is the clean division of what it captures:

• What it measures: polished diamond prices, by grade and size
• What it does not measure: rough prices, mining costs, or midstream margins
• What it signals: the directional health of polished demand and the downstream edge of the squeeze

That third bullet is why investors tracking natural diamond equities use it as a directional proxy. Long-term Rapaport Diamond Index data shows continued multi-year declines in average price levels into 2024. Note, though, that specific RAPI and index figures for 2025-2026 are not publicly available at the time of writing, so the November 2024 release remains the most recent detailed data.

The pressure on midstream polishers eventually flows upstream: the De Beers historic loss of $511 million in the same period illustrates that even the miner at the top of the allocation chain is not insulated from a collapse in polished demand sustained long enough to erode rough volume targets.

The reason the polished benchmark carries so much weight comes down to a single caveat.

De Beers rough sight prices are not publicly disclosed. There is no public index for what it costs to buy rough at a sight.

That gap matters enormously. With the rough side opaque, the Rapaport polished index is, in practice, the only number an outside observer can track to judge whether the pipeline is contracting or recovering. Understanding what it measures, and what it stays silent on, is essential before you draw any conclusion from it.

Reading the pipeline: what constrained supply and a battered polished index tell you together

Put the pieces together and a coherent picture emerges. You now understand three structural conditions at once: rough supply concentrated among fewer effective sellers after the Alrosa sanctions; polished prices still deeply negative year-on-year, down between roughly 15% and 27% across size categories as of November 2024, despite small monthly upticks; and Indian polishing capacity acting as the pressure valve that shuts down when the spread gets too thin.

The forward-looking questions are genuinely open. Do the small November 2024 monthly recoveries mark the start of a real polished rebound, or just noise? Will De Beers be forced into deeper production cuts if sightholders keep resisting above-market boxes? Has the margin floor for Indian polishers shifted permanently lower?

No public data resolves these. What you can watch are two signals:

• Rapaport index movements by size category, because they reveal where lab-grown pressure is sharpest
• De Beers production guidance, because it is the clearest proxy for miner confidence in rough price sustainability
• Indian polishing capacity signals, because factory closures and reduced shifts show when the spread has become unworkable

Be honest, though, about what you cannot see. The public picture has real gaps:

• De Beers sight prices, never disclosed
• Alrosa’s post-2022 sales volumes and destinations, no longer published
• Rapaport index updates for 2025-2026, not yet public
• Quantified midstream margin data, described only qualitatively

The combination of constrained supply, compressed polished prices, and an opaque rough layer means the public signals here are partial. Treating the Rapaport polished index as the whole story, without accounting for the rough side, is a systematic analytical error. You leave with a framework, not a forecast: the mechanisms to track, the gaps to respect, and the structural questions that stay open regardless of any single month’s move.

Investors applying this pipeline framework to equities quickly discover that diamond mining stock valuation cannot rely on standard commodity-sector multiples, because the opaque rough pricing layer and concentrated supply mechanics produce a risk profile that standard discounted cash flow models systematically misprice.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions. Past performance does not guarantee future results, and forward-looking statements are speculative and subject to change based on market developments.