40 Fun Facts About Diamonds

While a decoy sailed under guard by steamer, how did the 3,106-carat Cullinan rough reach London in 1905?

By registered post, in a plain box: detectives shadowed the RMS Kenilworth Castle and its ceremonially guarded parcel, and even the captain never knew his cargo was the decoy.

Harry Winston sent the Hope Diamond to the Smithsonian in 1958 wrapped in plain brown paper; how much was the postage?

$2.44 was the postage; the rest of the $145.29 bill was insurance for $1,000,000, and the brown-paper package itself is now kept in the Smithsonian's collection.

Which French queen's name was wrecked by the 1785 Affair of the Diamond Necklace, a con she never took part in?

Marie Antoinette had turned the necklace down; the adventuress Jeanne de Valois-Saint-Rémy forged her signature to get it from the Crown jewellers, and the queen's gossip-battered reputation never recovered.

Which 1985 Madonna video restages Marilyn Monroe's pink-gown number from Gentlemen Prefer Blondes, suitors and all?

Material Girl copies the Gentlemen Prefer Blondes staging, Madonna ringed by tuxedoed suitors, intercut with a Hollywood director trying to win the actress's heart.

Blood Diamond (2006), with Leonardo DiCaprio as a Rhodesian smuggler, is set in which country's 1999 civil war?

Sierra Leone's war pits government loyalists against insurgents, and DiCaprio's Danny Archer is jailed in Freetown for trying to run diamonds into Liberia.

Which US state's Crater of Diamonds park lets visitors keep any gem they find, on the field that yielded the Uncle Sam?

Arkansas bought the Murfreesboro site in 1972; the 40.23-carat Uncle Sam, dug there in 1924, remains the largest diamond ever found in the United States.

On Friedrich Mohs's scratch-hardness scale, diamond sits at which number, a single step above corundum?

10 was set arbitrarily as the top of the scale, yet in absolute hardness diamond is about four times harder than corundum, which rates 9.

The carat used to weigh diamonds is named after the seed of which tree, long used by gem traders as a weight?

Carob seeds were trusted because their mass was believed to vary little, and the word reached English via Italian carato, Arabic qīrāṭ and Greek kerátion.

Who founded De Beers Consolidated Mines in 1888, bankrolled by Alfred Beit and the Rothschild bank?

Cecil Rhodes formed it by merging his claims with rival Barney Barnato's, and served as the company's first secretary and chairman.

From 1888 until the early 2000s, roughly what share of the world's rough diamond distribution did De Beers control?

80–85% was enough to count as a monopoly, and the grip only loosened in the 21st century as Canadian and Australian producers sold outside the De Beers channel; by 2000 its share had slipped to about 63%.

De Beers adverts told men what slice of income to spend on a ring; how much did the 1980s Japanese version ask?

Three months' income was the Japanese figure against two in America; the whole idea that a man should spend a set fraction of his annual income on a ring began in De Beers marketing of the mid-20th century.

Grace Kelly wore her real Cartier engagement ring from Prince Rainier on screen in which 1956 film, her last?

High Society, a musical remake of The Philadelphia Story, reached cinemas shortly after her wedding and was her final professional appearance.

Who bought Elizabeth Taylor a 69-carat pear-shaped diamond in 1969, a day after Cartier outbid him for it at auction?

Richard Burton paid Cartier $1.1m for the stone it had won for $1,050,000, then a record for a publicly sold jewel, and crowds queued in New York and Chicago to see it.

Who first sang 'Diamonds Are a Girl's Best Friend' on Broadway in 1949, four years before Marilyn Monroe filmed it?

Carol Channing introduced the Jule Styne and Leo Robin number in the original Gentlemen Prefer Blondes, and recorded it again in 1974 for the revised musical Lorelei.

Which Australian singer-songwriter wrote the lyrics to Rihanna's 2012 hit 'Diamonds' in a reported 14 minutes?

Sia Furler joined producers Benny Blanco and Stargate at the session, and Rihanna copied her demo vocal so closely that Sia reportedly thought her own recording had been released.

The Koh-i-Noor was recut on Prince Albert's orders after its dull cut disappointed crowds at which 1851 London event?

The Great Exhibition showing was such a let-down that Punch mocked the stone; Coster's 38-day recut then shrank it from 186 old carats to 105.6.

Hong Kong tycoon Joseph Lau paid a record $48.4m in 2015 for the 12-carat 'Blue Moon' and renamed it after whom?

His daughter Josephine, then seven, also lent her name to a 16-carat pink diamond Lau had bought the day before for $28.5m, duly renamed the Sweet Josephine.

Queen Elizabeth II revealed in 1958 that her family called the Cullinan III and IV brooch by what nickname?

Granny's Chips slipped out during a state visit to the Netherlands, home of the Asscher firm that had cleaved and polished the rough stone fifty years earlier.

What did farmer Schalk van Niekerk pay a Griqua shepherd in 1869 for the rough Star of South Africa?

500 sheep, 10 oxen, a horse bought an 83.5-carat rough that Van Niekerk sold on for £11,200, and the find set off the rush that dug the Big Hole.

Diamond conducts heat about five times better than which metal, the most thermally conductive of all the metals?

Silver trails natural diamond's 2,200 W/(m·K) by a factor of five, which is why a jeweller's thermal probe can separate a real stone from most imitations in seconds.

Who focused sunlight through a lens to burn a diamond in oxygen in 1772, proving it is pure carbon?

Antoine Lavoisier found the only product of the combustion was carbon dioxide; the English chemist Smithson Tennant repeated and extended the experiment in 1797.

Which gem lab devised the 'four Cs' of cut, clarity, colour and carat weight as a diamond grading standard in 1953?

GIA, the Gemological Institute of America founded in 1931, also introduced the D-to-Z colour scale, which starts at D to break from the older A, AA and AAA labels.

Roughly 84% of the world's rough diamonds pass through which European city's 'Square Mile' beside its Central Station?

Antwerp's Diamantkwartier covers a few square blocks, and although the polishing has mostly moved to cheaper countries, about half the rough comes back there to be cut.

Which Gujarat city on the Tapti river cuts and polishes about nine in every ten of the world's diamonds?

Surat handles roughly 90% of the world's cutting and polishing, work that left the old European centres as their wages rose, while the city's other big trade remains textiles.

The Argyle mine, which closed in 2020 after supplying over 90% of the world's pink diamonds, was in which country?

Australia's remote north-west hosted it for 37 years, during which it also yielded champagne, cognac and rare blue stones and was at times the world's biggest diamond producer by volume.

Which country's Karowe mine produced both the 1,111-carat Lesedi La Rona in 2015 and a 2,492-carat stone in 2024?

Botswana's Karowe pit, run by Canada's Lucara, found a trio of 300-carat-plus stones in a single week of November 2015; Graff later cut the biggest into a 302-carat emerald cut and 66 smaller gems.

Ekati, the first diamond mine in Canada, opened near Lac de Gras in which territory, 200 km south of the Arctic Circle?

Northwest Territories' Ekati lies 310 km north-east of Yellowknife, on pipes that geologists Chuck Fipke and Stewart Blusson discovered and kept a stake in until 2014.

Lady Gaga wore which jeweller's 128-carat yellow diamond to the 2019 Oscars, only the third person ever to put it on?

Tiffany & Co. had let only Mary Whitehouse at a 1957 ball and Audrey Hepburn, in 1961 publicity shots for Breakfast at Tiffany's, wear it before; Beyoncé became the fourth in a 2021 campaign.

A gang ram-raided which London attraction in 2000 for a 203-carat De Beers gem, unaware police had planted replicas?

The Millennium Dome's riverside De Beers show held the flawless 203-carat Millennium Star, but the Flying Squad had replaced the gems and hidden 20 armed officers behind a false wall.

Which company's Tracy Hall made the first commercially viable synthetic diamonds in 1954 with a 'belt press'?

General Electric had chased synthesis since a 1941 pact with Norton and Carborundum, and Hall's grit, squeezed in a hydraulic press at its Schenectady labs, was announced in February 1955.

Which Danish charm-bracelet jeweller said in May 2021 it would phase out mined diamonds in favour of lab-grown?

Pandora made the switch in the wake of De Beers, long a critic of synthetics, launching its own lab-grown jewellery brand, Lightbox, in 2018.

Which diamond look-alike, grown by a Soviet 'skull crucible' method and mass-produced since 1976, is the commonest fake?

Cubic zirconia rates 8 to 8.5 on the Mohs scale and is usually colourless, and since 1976 it has been the most important competitor to diamond both gemologically and economically.

Labs beat Earth's core pressure by squeezing a sample between two diamonds in a cell named for which smith's tool?

Anvil cells press two gem-quality diamonds tip to tip on a sample smaller than a millimetre, reaching 640 gigapascals against the roughly 360 at the centre of the Earth.

BPM 37093, nicknamed after a Beatles song because its crystallised core is one vast diamond, is what kind of star?

A white dwarf with a radius of some 4,000 km, it pulsates, and in 2004 astronomers used those vibrations to estimate that about 90% of its mass had crystallised.

Which 100-km Siberian crater may hold Earth's largest diamond deposit, trillions of carats from an asteroid strike?

Popigai's shock pressures turned carbon in the ground to diamond within 13.6 km of the impact point in the late Eocene, and the whole area stayed off limits for decades.

British sailors named Honolulu's Diamond Head in 1825 after mistaking beach crystals of which mineral for diamonds?

Calcite crystals in the sand beside the crater, known as Lēʻahi in Hawaiian, were worthless, and the sailors' first choice of name was Diamond Hill.

Which Belgian engineer's 1919 book Diamond Design fixed the proportions of the 'ideal' round brilliant?

Marcel Tolkowsky, from a family of Polish-Jewish cutters, balanced brilliance against fire in his calculations, and his American Standard remains the benchmark in North America.

Which country's king received the 545-carat Golden Jubilee, long the largest cut diamond, for 50 years on the throne?

Thailand's Bhumibol Adulyadej got the brown stone from a group of businessmen, after it had been exhibited to mark De Beers' centenary in 1988.

Augustus III bought the largest natural green diamond known at Leipzig in 1742; which city's Green Vault displays it?

Dresden Castle's New Green Vault houses the 41-carat stone, of Golconda origin and named after the Saxon capital where it has spent most of two centuries.

Which family's 80-year control of De Beers ended in 2011 when Anglo American bought its 40% stake for $5.1bn?

Oppenheimer control began when Ernest took the chairmanship in 1929, and the sale left Anglo American with 85% of De Beers beside a 15% government holding.