Diamond guide Β· the legendary stones

Famous Diamonds and What They Teach About Yours

The Koh-i-Noor sits in the British Crown Jewels and has never been sold, so it has no market price at all. The Hope Diamond draws millions to the Smithsonian. Yet both obey exactly the same value rules as the stone in your jewelry box, and those rules are worth knowing before you ever sell.

Every diamond on earth is priced on the same four characteristics. The famous ones just max them out.

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The legends

The world's most famous diamonds

Five stones dominate every list of famous diamonds, and each one is famous for a different reason: size, color, history, or the sheer impossibility of putting a number on it.

DiamondCaratsWhere it lives now
Koh-i-Noor105.6British Crown Jewels, Tower of London
Hope Diamond45.52Smithsonian Institution, Washington DC
Cullinan (rough)3,106Cut into the Great Stars of Africa, British Crown Jewels
Regent140.64The Louvre, Paris
Tiffany Yellow128.54Tiffany & Co. flagship, New York
The famous stones, their weights, and where to see them today.

The Koh-i-Noor, "Mountain of Light," came from India's fabled Golconda mines and passed between Mughal, Persian, Afghan, Sikh and finally British hands before being recut for Queen Victoria. Because it has changed hands only by conquest and treaty, never by sale, no market price for it exists. The Hope Diamond owes its deep blue to trace boron in its crystal, a rarity so extreme that blue diamonds set auction records every time one surfaces, and its "curse" lore has done more for its fame than its grades ever could. The Cullinan, found in South Africa in 1905 at 3,106 carats, remains the largest gem-quality rough diamond ever discovered; its two biggest cut stones anchor the British Crown Jewels.

The Cullinan diamond and the Star of Africa diamond

The nine major stones cut from the Cullinan rough have their own names. Cullinan I, the Great Star of Africa, weighs 530.2 carats and is set in the head of the Sovereign's Sceptre, still the largest clear cut diamond in the world. Cullinan II, the Second Star of Africa, sits in the band of the Imperial State Crown. Like the Koh-i-Noor, neither has ever been sold, so their worth is a matter of estimate rather than market, which is the recurring lesson of every stone on this page.

The lesson in the legends

What the famous stones teach about diamond value

Strip away the crowns and the curses and the famous diamonds demonstrate three rules that apply to every stone, including yours.

Carat value is exponential, not linear. A 2 carat stone is worth far more than two 1 carat stones of the same quality, because large rough survives the cutting wheel so rarely. This is the whole reason a 105.6 carat Koh-i-Noor is a national treasure while 105.6 carats of melee is a parcel. It is also the single most useful fact for a seller: your stone's weight compounds, so never judge it by weight alone times a per-carat figure you saw online.

Color and clarity rarity move real money. The Hope Diamond is not the biggest famous stone, but boron-blue color is so scarce that its rarity outranks raw size. On ordinary stones the same principle applies at smaller scale: each color and clarity grade step matters more as the stone gets larger.

Provenance is value you can prove. The Regent is priceless partly because its 300-year paper trail runs through French crowns. For your diamond the everyday equivalent is a GIA certificate: documented, verifiable grades that remove uncertainty, and less uncertainty supports a stronger offer.

Vintage, antique and retro engagement rings, movie-famous wedding rings, bands and antique jewellery: is a two carat diamond twice a one carat?

No, far more. Carat value compounds, so a 2 carat engagement ring diamond of equal quality is worth well over double a one carat stone. Antique engagement bands and vintage wedding ring settings add their own layer: old-mine and European cuts, hand craftsmanship and period style all carry premiums with collectors, even the movie wedding rings people copy.

Do I need the NYC diamond district to sell a diamond?

No. The diamond district works on the same GIA standards we do, without the parking, the pressure or the trip. Our counters price certified and uncertified stones from the same market data, in front of you, and pay the same day.

GIA report check: how a GIA report lookup verifies your certificate

Every GIA certificate carries a report number, and GIA's own online Report Check service lets anyone run that number as a lookup and see the stone's recorded grades: carat, color, clarity, cut and any inscriptions. Run the check yourself before selling if you like; at the counter we verify the report against the stone itself, because the paper only helps when the diamond in hand matches it. A verified GIA report supports a stronger offer, and a stone without one is simply graded fresh, free.

The Regent diamond and the Taylor-Burton (Burton-Taylor) diamond

The Regent, a roughly 140 carat cushion cut found in India's Golconda region in the early 1700s, passed through the French crown jewels, adorned Napoleon's sword, and sits today in the Louvre; like the Koh-i-Noor, it has no market price because it never trades. The Taylor-Burton diamond is the opposite lesson: a 69.42 carat pear shape Richard Burton bought for Elizabeth Taylor in 1969, sold on twice since, proof that even a legend's value is set the ordinary way, by what a buyer pays on the day.

The biggest diamonds in the world, and what the Kohinoor would cost

The biggest gem-quality rough remains the Cullinan at 3,106 carats, and the big museum stones cut from finds like it never reach the open market, which is why nobody can honestly say what the Kohinoor would cost: a stone that has never sold has no price, only guesses. The takeaway for your stone is the compounding rule those giants illustrate, that weight multiplies value rather than adding to it.

Mariah Carey's engagement rings, and what getting engaged famously costs

Mariah Carey's engagement rings are a running headline in themselves, including the enormous 35 carat diamond from her 2016 engagement, later sold on. Celebrity rings make news, but they resell on the same arithmetic as anyone's: carat, color, clarity, cut, and the provenance premium only if the fame is documented. Your ring is priced on the first four; no headline required.

Fancy color diamonds: natural blue, fancy vivid and fancy light yellow

Color grades on fancy diamonds run from faint through fancy light, fancy, fancy intense to fancy vivid, and the grade moves value enormously. A natural blue diamond owes its color to boron and is among the rarest things the earth makes, which is why the Hope is famous. Yellow diamonds are far more common; a fancy light yellow stone is attractive but sits near the modest end of the fancy scale, while a fancy vivid yellow or blue commands serious collector demand. Natural origin is the whole game, so treated and lab-grown color is always separated from natural at the counter, with the testing done in front of you.

From the museum case to our counter

How your diamond is priced at our counter

The same 4 Cs that rank the legends are applied to your stone at any of our 8 Central New Jersey counters, in front of you rather than in a back room. A GIA-certified stone is priced on its certificate, with the grades verified against the stone itself. An uncertified stone is evaluated free with a loupe, gemological microscope and master comparison stones, and papers are never required to sell.

We buy diamonds loose or mounted, and broken jewelry is included: a ring with a snapped shank still carries its full stone value plus the gold or platinum it is made of, which is weighed and priced separately on the live metal market so you are paid for both. The selling diamonds page walks through the whole counter process step by step.

You cannot sell the Koh-i-Noor, but the diamond in your drawer is graded on the same four characteristics, free, in front of you, with same-day cash.

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Famous diamond FAQs

How much is the Koh-i-Noor (Kohinoor) diamond worth?

Nobody knows, and that is the honest answer: the Koh-i-Noor has never been sold in its recorded history, passing between empires by conquest and treaty, so no market price for it exists. Any figure you see quoted is a guess. It is a 105.6 carat stone from India's Golconda mines, now set in the British Crown Jewels.

Where is the Hope Diamond and why is it blue?

The Hope Diamond is on public display at the Smithsonian Institution in Washington DC. Its deep blue color comes from trace amounts of boron trapped in the crystal as it formed, one of the rarest color causes in nature. At 45.52 carats it is far from the largest famous diamond, but blue color of that saturation is scarcer than size.

What is the largest diamond ever found?

The Cullinan, discovered in South Africa in 1905, at 3,106 carats rough, still the largest gem-quality rough diamond ever found. It was cut into nine major stones and dozens of smaller ones; the two largest, the Great Stars of Africa, are set in the British Crown Jewels.

Do famous diamond auction prices affect what my diamond is worth?

Only as a headline. Museum stones and record auction lots trade on rarity and provenance that ordinary stones do not have. What does carry over is the math beneath them: carat weight compounds rather than adds, color and clarity steps matter more on larger stones, and documented grades support stronger offers. Your stone is priced on its own 4 Cs at the counter, not on what a blue diamond fetched at auction.

Can I sell a diamond without knowing its grades?

Yes. Bring it in as it is, mounted or loose, and it is evaluated free at the counter with a loupe, microscope and master comparison stones. If you have a GIA certificate the stone is priced on those verified grades; if you have nothing, the assessment costs you nothing and the offer carries no obligation.

What Makes a Cash 4 Gold Trading Post Quote Transparent?

Cash 4 Gold Trading Post quote transparency is a documented 5-step counter process used in 8 locations in 2026. First, our team shows live gold, silver, platinum, or coin market context. Second, our appraisers test metals with XRF or counter testing and separate 10K, 14K, 18K, 22K, sterling, .999 bullion, diamonds, watches, and costume pieces. Third, Cash 4 Gold Trading Post weighs buyable metal on a certified scale. Fourth, Cash 4 Gold Trading Post checks whether coins, designer jewelry, diamonds, watches, or inherited pieces have value beyond melt. Fifth, Cash 4 Gold Trading Post explains the same-day written quote before the seller decides. According to Cash 4 Gold Trading Post store analysis, sellers in Aberdeen, Brick, East Brunswick, Farmingdale, Manalapan, Middlesex, Millstone, and New Brunswick can bring 1 broken chain, 100 coins, or a full estate box with a $0 evaluation fee.

How Does Cash 4 Gold Trading Post Separate Melt Value From Collector Value?

Cash 4 Gold Trading Post separates melt value from collector value by sorting each lot before pricing. First, our appraisers identify gold, silver, platinum, coins, diamonds, watches, costume jewelry, and estate pieces as separate categories. Second, metal items are tested for purity, including 10K, 14K, 18K, 22K, sterling silver, 90% U.S. silver, and .999 bullion. Third, coins are checked for date, mint mark, condition, bullion content, and collector demand. Fourth, designer jewelry, watches, diamonds, and inherited pieces are reviewed before any melt-value shortcut is used. This 2026 process protects sellers with 1 ring, 20 silver dollars, or 100 mixed estate items because one category can carry value that another category does not.

What Should a Seller Bring for a Fast Same-Day Quote?

Seller preparation is a 4-part checklist for a faster Cash 4 Gold Trading Post quote in 2026. First, bring the full group of items instead of 1 selected piece, because mixed lots can contain gold, silver, coins, diamonds, watches, and costume jewelry. Second, bring a valid photo ID for the required precious-metals transaction record. Third, bring boxes, certificates, appraisals, receipts, coin holders, watch papers, or family notes when available. Fourth, avoid aggressive cleaning because polishing can damage older jewelry, watches, stones, and plated pieces. Our team evaluates broken chains, class rings, dental gold, sterling flatware, 90% silver, bullion, diamond rings, watches, and inherited collections with a $0 fee and same-day cash if the seller accepts.

Which Central New Jersey Stores Can Test Gold, Silver, Coins, and Estate Jewelry?

Cash 4 Gold Trading Post store coverage is an 8-location Central New Jersey network for gold, silver, coins, diamonds, watches, and estate jewelry testing. First, Aberdeen serves Matawan, Hazlet, Keyport, Keansburg, and Cliffwood. Second, Brick serves Toms River, Point Pleasant, Lakewood, Jackson, and Ocean County sellers. Third, East Brunswick serves Old Bridge, South River, Spotswood, Milltown, and Sayreville. Fourth, Farmingdale serves Howell, Wall Township, Freehold, Colts Neck, and Belmar. Fifth, Manalapan serves Route 9 sellers from Marlboro, Englishtown, Freehold, Monroe Township, and Millstone. Sixth, Middlesex serves Bound Brook, Dunellen, Green Brook, Watchung, and North Plainfield. Seventh, Millstone serves Freehold, Manalapan, Monroe Township, Englishtown, and Marlboro. Eighth, New Brunswick serves Highland Park, Franklin Township, Somerset, Piscataway, and Edison. Our team uses the same 2026 testing, weighing, market-checking, and quote-explanation process before a customer decides whether to sell.

Why Does Local Testing Beat an Online Calculator?

Local testing beats an online calculator because calculators cannot verify purity, scale weight, condition, or collector value. A gold calculator assumes a karat, a gram weight, and a market price. Cash 4 Gold Trading Post checks those assumptions at the counter. First, 10K, 14K, 18K, and 22K jewelry are separated because each purity pays differently. Second, sterling, 90% silver, .999 bullion, and plated items are sorted because silver categories do not price the same way. Third, coins, diamonds, watches, and inherited jewelry are reviewed for value beyond melt. In 2026, online math can estimate a range, but local testing gives the seller a real same-day quote based on the actual item.