Learn Everything About the Dazzling and Rare 100 Carat Diamonds Sold at Sotheby's

Brief History of Diamonds

Diamonds were first discovered in the India around the 4th century BCE. Ancient Indians believed diamonds had supernatural powers including protection from evil and granting courage and strength. By the Middle Ages diamonds become a symbol of status and wealth in Europe while the Renaissance marked a turning point for diamond cutting improvements in Venice. India remained the only source of diamonds until the 1720s, when diamonds were discovered in Brazil. By the mid-18th century, Brazil became the world's largest diamond supplier, a position it held until the discovery of diamonds in South Africa in the late 19th century. The Brazilian diamond mines played a key role in global diamond supply, helping to meet the increasing European demand for diamonds during this period. By the 1880s, South Africa became the global leader in diamond production, leading to the establishment of the De Beers Consolidated Mines in 1888.

In 1947, De Beers launched its now infamous Ad campaign, “A Diamond is Forever.” This campaign transformed diamonds from luxury goods to essential symbols of love, popularizing diamond engagement rings. With Hollywood’s help, the diamond engagement ring became a norm, associating diamonds with eternal love and commitment. The global diamond jewelry market was $340 billion in 2022 with sales of engagement rings valued at about $25 billion.

The 100 Carat Diamond

At Sotheby's our focus is sourcing and selling the highest quality diamonds, including diamonds from the top luxury brands. At the very top end of the luxury diamond market is the 100 carat diamond. Sotheby's sold the first 100 carat diamond in 1990 and remains one of the leaders in selling the largest and highest quality diamonds in the world at often record breaking prices.

Size of 100 carat diamond

A 100 carat diamond is about the size of a small egg or a large grape and weighs about 20 grams (one carat is ~ 0.2 grams). A round brilliant cut 100-carat diamond is about 40-45 millimeters in diameter (about 1.6 to 1.8 inches across) and around 25 millimeters deep. For other cuts like emerald or oval, a 100-carat diamond would appear even larger due to its elongated shape, but the actual dimensions would still depend on the specific proportions and depth of the cut.

Nature versus Nurture

For a natural diamond to reach a weight above 100 carats after being cut and polished is a marvel of nature. Collectors are fascinated and drawn to these dazzling and rare diamonds since each is truly a one of a kind. The Perfection and Harmony of Nature and Man together is aptly exemplified by the magic of these alluring diamonds, one of the hardest and most precious materials known to mankind.

Highest Quality Diamonds

Large flawless diamonds are the paragon of white diamonds. Rarer still are D/Flawless Type IIa diamonds. These are the most chemically pure type of diamonds and have exceptional optical transparency. Extraordinarily limpid, they have been compared to pools of crystal waters or drops of frozen ice. First identified as originating from the famed Golconda region of India, Type IIa diamonds are now recovered in all major diamond producing regions. Two famous examples of Type IIa diamonds are the Cullinan I and the Koh-i-Noor, both part of the British Crown Jewels.

Sotheby's 100 Carat Diamonds

Sotheby's sold its first 100 carat diamond in 1990 for nearly 16 million CHF. The Mouawad Splendour was a 101.84 carat, D color, Interntally Flawless, pear-shaped diamond sold in Geneva. After this historic sale, the next 100 carat diamond was sold in 1993, The Star of Happiness. This modified rectangular brilliant shape, D color, Internally Flawless 100.36 carat diamond sold for 17.8 million CHF (US$118,397 per carat) in Geneva. In 1995, Sotheby's sold Star of the Season for US$ 16.4 million or US$164,223 per carat. The 101.10 carat pear shaped diamond D color, Internally Flawless held the record for price per carat for nearly 15 years.

The magic of the carat number “100” makes for an auction legend. The appearance of a 100 carat D-Flawless diamond is always an international newsworthy event. Only very few D-Flawless or Internally Flawless 100 carat diamonds have appeared and sold at auction over the decades. Less than one-half of one percent of all stones over one carat submitted to GIA annually are D, Internally Flawless, or D, Flawless.

Sotheby's remains a leader in selling the largest highest quality diamonds. Take a closer look at eight of the most impressive 100 carat diamonds sold by Sotheby's since 2011.

118.28 Oval Diamond $30.8 million

In 2013, Sotheby's sold a 118.28 carat oval diamond for 238.7 million HKD or $30.8 million. This is the most expensive diamond over 100 carats sold by Sotheby's. The unmounted oval brilliant cut diamond is D color, Flawless clarity, with Excellent Polish and Symmetry. A separate letter states that this diamond is a type IIa diamond. this oval diamond is described as having a pleasing outline, very nice face-up brilliance and great material showing a "watery" transparency. GIA report numbered 2155581489, dated 21 August 2013

The rough diamond was discovered in Southern Africa in 2011 and initially weighed 299 carats as a rough diamond. The best skilled diamond artisans spent months cutting and polishing the diamond to guarantee the greatest standards of proportionality and beauty.

100.20 Carat Emerald Cut Diamond $22.1 million

In 2015, Sotheby's sold a 100.20 emerald cut diamond for $22.1 million. The diamond was D color, Internally Flawless and Type IIa, This is the only emerald cut diamond Sotheby's has sold over 100 carats. The diamond was sold mounted as a ring set in platinum and inscribed 100.20 cts on the inner shank.

THE VICTOR 10239 $15.7 million

In 2020, Sotheby's sold The Victor 10239, an oval 102.39 carat diamond for for 121.6 million HKD or about $15.7 million. The impressive oval diamond was D color, flawless, excellent polish and symmetry and a Type IIa diamond.

This 102.39 carat diamond originally came from a 271 carat rough: the largest ever recovered from Canada’s Victor Mine. The rough diamond was then skillfully cut by Diacore to perfect its beauty. The process of designing a diamond from a rough, cutting and then polishing it takes months, if not years. This 102.39ct diamond combines an elliptical girdle outline with triangular and kite-shaped facets to create an oval brilliant-cut. According to the GIA, the oval brilliant channels and intensifies color in diamonds. Thus, transforming the rough through this manufacturing process, Diacore brought out the diamond’s inherent perfection.

The Graff Vivid Yellow $13.3 million

In 2013, Sotheby's sold the Graff Vivid Yellow, a 100.09 carat diamond, fancy vivid yellow modified cushion cut brilliant natural color, VVS2 clarity for 14.5 million CHF or $13.3 million. Of exceptional beauty and extraordinary fire and brilliance, this gem is one of the largest fancy vivid yellow diamonds in the world. The Graff Vivid Yellow is listed in Ian Balfour's reference book Famous Diamonds, published in 2008, as one of the few rare yellow diamonds greater than 100 carats.

Juno Diamond $13.0 million

In 2022, Sotheby's sold the Juno Diamond, a pear-shaped diamond weighing 101.41 carats for $13.0 million. The pear shaped diamond is D color, Internally Flawless and classified as a Type IIa diamond.

The Sun Drop Diamond (The Lady Dalal) $12.4 million

In 2011, Sotheby's sold the The Sun-Drop Diamond, the largest known Fancy Vivid Yellow pear shaped diamond at 110.03 carats for 11.3 million CHF or $12.4 million. The diamond was renamed to The Lady Dalal after the sale.

The Sun-Drop was unveiled to the world at London's Natural History Museum where it was exhibited in the famous 'Vault Gallery' from February through August 2011. Historically significant with regard to its size and colour, Alan Hart, head of collections for the Mineralogy Department, was delighted to display such a stone. "When you look at a diamond like this", he stated in the Museum's press release, "you are not only looking at a unique piece of art, you are looking at the fascinating science that brought this stone to us. The Sun-Drop diamond was formed deep within the Earth's crust 1-3 billion years ago. As it grew, it incorporated nitrogen into its carbon crystal structure. It is these nitrogen impurities that give the diamond its yellow colour as they modify light, absorbing the blue part of the visible spectrum. The diamond then travelled on a long journey upwards in a slushy rock magma. After it was found within a kimberlite pipe (a type of volcanic rock), it was expertly studied and cut, bringing the diamond to life."

The Key 10138 $12.2 million

In 2021, Sotheby's sold The Key 10138, a pear shaped 101.38 Carat diamond for 95.1 million HKD or anbout $12.2 million. The Unmounted diamond is D Color and Flawless and classified as a Type IIa diamond. The Key 10138 is second largest pear shaped diamond ever to appear on the public market and came from the world-leading diamond company Diacore. Diamonds of this size and quality are exceptionally rare, with only ten 100 carat+ examples ever having come to auction to date. This diamond also broke the record for setting the highest price achieved for any jewelry or gemstone purchased with cryptocurrency.

102.34 Carat Round Diamond

In 2018 Sotheby's sold a round 102.34 carat round diamond, D Color, Flawless, Type IIa diamond with excellent cut, polish and symmetry. This is the largest round diamond shaped diamond, D color and flawless to ever be graded by GIA. While the final purchase price remains private, it sold for a price per carat that far exceeded any colorless diamond sold at auction. Mined in Botswana, it weighed 425.40 carats in the rough. Intense study and mapping by Sotheby’s Diamonds partner Diacore resulted in 25 stones – a process that took more than 6 months of careful, painstaking cutting and polishing.

100 Carat Diamond Price

The price for a 100 carat diamond or larger is most dependent on the quality of the diamond including all aspects of stone including color, clarity, cut and of course the size. At the very top end of the diamond market, the rarest and most exceptional quality 100 carat diamonds have sold from $12 million to over $30 million at Sotheby's.

Prices for rare stones like 100 carat diamonds can be difficult to forecast due to few qualified buyers and the range of assets available to this population. The global population of billionaires was about 2,800 in 2023 with combined wealth of $14.2 trillion. Along with billionaires, the number of ultra high net worth individuals (UHNWIs) with net worth exceeding $30 million is about 426,000 globally. Competition from multiple motivated buyers can drive prices above expected market values while the converse can happen with interest from just one buyer.

Buying and Selling Rare Diamonds at Sotheby's

Sotheby's often has impressive rare diamonds available at auction, including high quality Type IIa diamonds that are over 20 carats in size. If you don't want to wait until the next auction, Sotheby's also has a curated selection of high quality diamonds available for immediate purchase on marketplace. If you would like to source a special High Jewelry diamond ring or other high jewelry creation, a salon specialist would be happy to assist. Sotheby's also provides custom high jewelry services and custom engagement ring services with loose diamonds. Sotheby's is able to source rare and impressive diamonds from its global supplier network so contact a salon associate or specialist for more details.

Explore upcoming jewelry at auctions in New York, London, Switzerland, Paris, and Hong Kong.
Contact a Salon Associate in New York, Zurich or Hong Kong to schedule an appointment.
Speak to Jewelry Specialist about selling a rare diamond.

Trust our worldwide network of leading jewelry specialists from a globally renowned auction house since 1744.