Markets, pricing & investment

The most widely used reference for polished diamonds is the Rapaport Price List. Rapaport describes it as the first diamond price list and states that its figures are high cash asking prices for well-cut white diamonds, quoted in hundreds of US dollars per carat, and that they are not a record of transaction prices. Dealers seldom trade at the list. They quote a stone as a percentage discount or premium to it, so the list works as a shared grid for negotiation. Rapaport publishes separate round and pear lists every Thursday and a parcel list monthly.

Trading platforms build indices from their own inventories. Rapaport's RapNet Diamond Index draws on prices posted on its Rapaport Trade network, and IDEX Online calculates its index with Avi Wohl of Tel Aviv University from asking prices in its own database, aggregated since February 2001 and refreshed hourly. For rough, the analyst Paul Zimnisky publishes a weekly index set at 100 on 31 December 2007 and built from long-term contract sales together with tender, auction and secondary-market trading. Colored stones have no equivalent benchmark. The GemGuide from Gemworld International prints bimonthly wholesale ranges instead, and the Fancy Color Research Foundation compiles a members' index from buying prices reported by wholesale firms.

Rough and polished prices trend together over years but can diverge for months. Large miners set rough prices at their own sales, while polished prices emerge from many private trades between manufacturers, dealers and jewelers. When cutters pay more for rough than the polished market later supports, the loss falls on the midstream, the firms between mine and retailer.

Bain and the Antwerp World Diamond Centre measured the whole ladder for 2010. Rough left the mines at US$12.0 billion, reached cutters at US$12.5 billion, left the cutting factories at US$17.5 billion, passed through polished dealers at US$18.2 billion, went into jewelry worth US$35.0 billion and reached consumers at US$60.2 billion. Operating margins were 22–26% in mining and 5–10% in retail, but 1–5% at every stage in between.

The squeeze on that middle shows in recent figures. Rapaport reported that its 1.00 ct index fell 23% in 2024 and 9.9% in 2025, and that about ten De Beers sightholders (contract buyers of rough) got no allocation for 2025 after missing their purchase thresholds. De Beers reported an average rough price index 12% lower in 2025 than in 2024 and an average realized price of US$142 per carat, down 7%; in the first half of 2026 it realized US$105 per carat, 32% below a year earlier. Realized prices also move with the mix of goods sold.

Gems are illiquid: an owner who needs cash cannot sell instantly at a quoted price, as with a listed share. A buyer has to be found, usually a dealer or jeweler who must resell at a profit, or an auction house that charges fees and may need months to schedule a sale. The bid-ask spread, the gap between what buyers offer and what sellers ask, is therefore wide, and it is widest for private owners selling stones they bought at retail.

The size of the wedge can be read off the trade's own accounts. In the Bain and AWDC figures for 2010, polished dealers handled about 30% of the money consumers spent on diamond jewelry and jewelry makers about 58%; the rest stayed with the retailer. Signet Jewelers, the largest US specialty jeweler, reported cost of sales at 60.5% of sales for the year to 31 January 2026, although that figure also covers store occupancy and distribution. At auction, Christie's and Sotheby's each charge buyers 28% on the first US$2 million of the hammer price, and the consignor pays a separate commission that is negotiated and not published.

Official guidance makes the same point without numbers. IRS Publication 561 states that the fair market value of jewelry is not the figure an appraiser sets so that an insurer can reimburse a loss.

Gold is fungible: one bar of a given weight and purity can replace another, so it trades on exchanges at a single price. Diamonds are not fungible. Weight, color, clarity, cut proportions, fluorescence and inclusions vary from stone to stone, and a grading report compresses those differences into categories that still leave room to disagree on price. Colored stones add origin, treatment and subjective color terms.

Price discovery, the process by which trading reveals a market price, is weak as a result. Most deals are private, the main platform indices are built from asking prices rather than completed transactions, and auction results cover mainly exceptional stones. The Financial Action Task Force and the Egmont Group of financial intelligence units, reporting on money laundering through the diamond trade, describe the market as closed and opaque and note that a lack of expertise outside it makes abuse harder to detect.

These features work against every attempt to package gems as financial products. Standardized contracts need interchangeable units, and investors need a dependable price at which they can exit. Ventures that tried to supply both, such as the Singapore exchange described below, have found trading volume hard to build.

Sellers of gems as investments usually make four claims: stones diversify a portfolio, hold value against inflation, pack great wealth into a small object, and can be carried across borders. The last two are physical facts. The Financial Action Task Force and the Egmont Group list the difficulty of tracing stones, and the combination of high value with small size, among the features that expose the diamond trade to money laundering. The same properties make gems a way to move wealth out of a country, legally or otherwise.

The first two claims are harder to test. Published trade indices rest largely on asking prices or on members-only dealer surveys, so statements about inflation protection rest on thin data. Recent figures show that prices can fall sharply: Rapaport's index for 1.00 ct diamonds lost 23% in 2024 alone, and De Beers cut its average realized rough price by 7% in 2025 and by a further 32% in the first half of 2026.

Gems also produce no income. An owner pays for insurance, for storage or a safe, and for the grading reports that make a stone saleable, and recovers none of that on resale. Those costs run whether prices rise or fall.

The Singapore Diamond Investment Exchange went live on 5 May 2016 as an electronic market for GIA-graded polished diamonds, held in Malca-Amit vaults in Singapore and at the Bharat Diamond Bourse in Mumbai and settled three business days after each trade. It was backed by Vertex Venture Holdings, part of the state-owned Temasek group, and its chief operating officer put expected turnover for 2016 at about US$250 million. No audited trading figures were published afterwards, and no primary announcement of its closure was found.

Tokenization links a digital token to a physical asset held by a custodian. Diamond Standard, a US company, sells coins at US$2,530 and bars at US$25,300 that contain sets of natural diamonds certified by GIA and IGI, a token called Carats priced from US$0.50 with a US$25 minimum, and a private fund with a US$100,000 minimum. It publishes a daily index, DIAMINDX, on the Bloomberg Terminal. Fractional ownership of this kind lowers the entry price, but the holder depends on the custodian, on the redemption terms and on the legal standing of the token, none of which a gemological report addresses.

Lenders treat gems as difficult collateral. A loan against a stone needs an agreed value, a way to confirm that the stone returned is the one pledged, and a buyer if the borrower defaults, and all three are harder to secure than with listed securities.

Pawnbrokers do this at the smallest scale. The UK Financial Conduct Authority reported in 2021 that the average British pawnbroking loan was made at 50% of the assessed value of the item, and that the average firm wrote about 5,400 agreements a year. FirstCash, the largest listed pawn operator, tells investors that it does not check a borrower's credit, relies instead on the marketability and expected sales value of the pledged goods, and takes forfeited collateral into inventory at the principal of the loan.

Inside the trade, specialist banks have financed the middle of the chain. Bain and the Antwerp World Diamond Centre found in 2011 that cutters and jewelry manufacturers, unlike miners and retailers, usually had no assets to pledge, and that a small group of diamond banks filled the gap with receivables finance and working-capital loans.

When a secured loan goes bad the lender has to sell, often quickly. Lenders therefore care most about what a stone would fetch in a fast sale, its liquidation value, rather than its retail replacement value.

A freeport is a bonded warehouse in which goods count as not yet imported, so customs duties and taxes fall due only when the goods leave. The Swiss Federal Audit Office, reviewing federal supervision of these sites, counted seven free ports and 194 open customs warehouses in Switzerland in 2018, against ten and 245 in 2014.

The best known is in Geneva. Ports Francs et Entrepôts de Genève SA is 87% owned by the canton, according to a 2017 report to the Geneva Grand Council, and holds artworks, antiquities, jewelry and watches under two regimes, ordinary warehousing and customs-bonded storage, with duties and value-added tax suspended until a sale. The same report set out the inventories that freight forwarders keep for customs, and proposed that those inventories name the owner of each consignment, which had not been required.

Gems are also kept with specialist vault and secure-logistics firms, such as Malca-Amit, which held the Singapore exchange's inventory, and in bank safe-deposit boxes. Freeports draw criticism because an owner can keep assets out of sight for years, and because the Swiss auditors returned twice to check whether supervision had improved.

The same stone can carry several legitimate values, and an appraisal should state which one it reports. Fair market value is the price property would sell for on the open market, agreed between a willing buyer and a willing seller, neither required to act and both with reasonable knowledge of the relevant facts; the US Internal Revenue Service uses that definition in Publication 561, its guide to valuing donated property. Replacement value is the cost of buying a comparable item at retail, and it is the figure insurers use. Liquidation value is what the stone would fetch in a quick or forced sale, and it is normally the lowest of the three.

The gaps between these numbers can be large. Publication 561 warns that the fair market value of jewelry is not the value set so that an insurer could reimburse the owner for a theft or a loss. It adds that gems and jewelry are specialized enough that a jewelry appraiser is almost always needed, that the appraisal should analyze the stone's color, weight, cut, brilliance and flaws, and that laboratory certificates and color photographs should be included. Donated property valued above US$5,000 needs a qualified appraisal. An owner who compares an insurance figure with a dealer's cash offer is comparing a replacement value with something close to a liquidation value.

The United States is one of the world's leading markets for polished diamonds, and the US Geological Survey expects it to remain a dominant gemstone consumer. It put apparent US gemstone consumption at US$9.4 billion in 2025, 47% below 2024, after a downturn that began in early 2023 and hit stones of one carat and under hardest.

The bridal segment is changing fast. The Knot Worldwide surveyed 10,474 US couples married in 2025 and found that 61% chose a lab-grown center stone for the engagement ring, spending an average of US$4,600 on those rings.

De Beers described US demand in 2025 as holding up, with strength in higher-end categories offsetting weakness at the lower end, and reported in July 2026 that natural diamond jewelry sales had returned to growth among independent US jewelers. It called Indian demand strong in both years. Chinese demand it described as muted in 2025 and still falling in the first half of 2026, with no significant recovery expected soon. Rapaport reported in January 2026 that Indian exports had slowed because of US tariffs and that Chinese appetite remained low, and noted that the Indian group Titan had launched a lab-grown brand, beYon. For the Gulf, De Beers reported only that rough trading in the first half of 2026 had been complicated by conflict in the Middle East; it published no consumer demand figure for the region.

Diamonds and colored stones do not move together, and within each group the top and the bottom of the market can diverge. Rapaport reported that in 2025 its index fell 20.3% for 0.30 ct diamonds and 26% for 0.50 ct stones, and that round 1.00 ct D–H SI diamonds fell 24.1%, while 3.00 ct stones rose 0.3%. It linked the weakness in smaller and lower-quality goods to competition from lab-grown diamonds.

Colored stones have no common price list, their prices depend heavily on origin and treatment, and the market is watched mainly through dealer guides and auction results. The longest comparison built from completed transactions comes from Luc Renneboog and Christophe Spaenjers, who used 3,952 Sotheby's and Christie's lots sold between 1999 and 2010 to build separate indices for white diamonds, colored diamonds and other gems. Average real returns in US dollars over the full period were 6.4% a year for white diamonds and 2.9% for colored diamonds, against 11.6% for gold and −0.1% for equities. From 2003 the figures were 10.0% for white diamonds, 5.5% for colored diamonds and 6.8% for other gems. Auction lots are drawn from the top of the market, so they describe what exceptional stones did, not what an average buyer would have seen.

De Beers Consolidated Mines was established on 12 March 1888, after the company Cecil Rhodes had built bought out Barney Barnato's Barnato Diamond Mining. By the time Rhodes died in 1902 it accounted for about 90% of the world's rough diamond production and distribution. For most of the 20th century it sold rough to invited buyers on term contracts through the Central Selling Organisation and bought other producers' output to hold supply off the market. In 1947 Frances Gerety, a copywriter at N. W. Ayer, wrote the slogan “A Diamond Is Forever”.

The model changed at the turn of the century. Bain and the Antwerp World Diamond Centre date the Supplier of Choice program to 2003: De Beers would promote its own brand rather than the category, and would stop buying and stockpiling the world's rough. Legal pressure came with the shift. On 13 July 2004 De Beers Centenary AG pleaded guilty in a federal court in Columbus, Ohio, to conspiring to fix industrial diamond prices in 1991 and 1992, and paid a US$10 million fine. In February 2006 the European Commission made binding a commitment to phase out purchases of rough from Alrosa; they stopped after 2008.

Anglo American holds 85% of De Beers and the government of Botswana 15%. Reporting on the first half of 2026, Anglo said the sale of De Beers was advancing.

Lab-grown diamonds have the same crystal structure as mined diamonds but can be produced to order, and their prices have followed production costs down. When De Beers launched its Lightbox brand in 2018 it priced lab-grown stones at US$800 per carat. In May 2025 it said wholesale lab-grown prices had fallen 90% since then, announced that it would close Lightbox, and said its Element Six subsidiary would leave the jewelry market and keep to industrial uses of synthetic diamond.

The analyst Edahn Golan has collected quarterly transaction prices from polishers in Mumbai and Surat since the third quarter of 2018. He reported that by mid-2026 wholesale prices were more than 97% below where they started: one-carat stones had gone from US$1,800 per carat to about US$80, and two-carat stones from more than US$3,000 to about US$85.

Cheap stones have taken share. Lab-grown center stones accounted for 61% of US engagement rings among couples married in 2025, which The Knot put at a 239% increase since 2020. De Beers now presents natural diamonds as a separate category from factory-made goods, and Rapaport has tied the sharpest falls in natural prices, in smaller and lower-quality stones, to lab-grown competition.

Gem investment fraud often runs through boiler rooms: call centers that cold-call targets and use scripted, high-pressure sales techniques. The products are typically colored diamonds, sapphires or parcels described as investment grade, sold far above what the trade would pay. The London Diamond Bourse, warning consumers about these schemes, says the prices charged can exceed 15 times the correct value, and that victims have lost tens and sometimes hundreds of thousands of pounds. To make a price look reasonable, buyers may be given grading reports from little-known laboratories that grade leniently, or valuation documents quoting retail replacement values. The promised resale, often through the same firm, does not happen.

The UK Financial Conduct Authority lists diamonds, alongside gold, fine art, wine and whisky, among products it does not regulate, and says buyers of them are not protected if something goes wrong and could lose all their money. Its warning signs include offers said to be open for a short time only, promises of high returns, calls out of the blue, and callers who say the target has been specially chosen. Reports from major laboratories can be checked against the issuing lab's own database, and an owner can test a stone's value by asking independent dealers what they would pay for it, not what they would charge.