Learn Everything About the Dazzling and Rare 100 Carat Diamonds Sold at Sotheby's
Learn more about record breaking 100 carat diamonds.
Brief History of Diamonds
Diamonds were first discovered in India around the 4th century BCE, where they were believed to possess supernatural powers, offering protection and strength. By the Middle Ages, they had become symbols of wealth and status in Europe, and the Renaissance ushered in advances in diamond cutting, particularly in Venice. India remained the sole source of diamonds until the 1720s, when Brazil emerged as a major supplier, dominating the global market until the late 19th century. The discovery of diamonds in South Africa in the 1880s shifted global production, culminating in the founding of De Beers Consolidated Mines in 1888.
A pivotal moment came in 1947 when De Beers launched its iconic advertising campaign, “A Diamond is Forever,” forever linking diamonds with romance and commitment. The campaign’s success, bolstered by Hollywood’s glamour, transformed diamonds into must-have symbols of enduring love. As of 2025, the global diamond jewelry market was valued at $389.5 billion, with diamond engagement ring sales accounting for a significant segment of the market. Among the rarest and most valuable diamonds in the world today are those that weigh 100 carats or more. These rare gems are not only geological marvels but also represent the pinnacle of luxury and craftsmanship in the diamond industry.
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 made history in 1990 with the sale of its first 100 carat diamond: the Mouawad Splendour, a 101.84 carat D color, Internally Flawless, pear-shaped stone that sold for nearly 16 million CHF in Geneva. This landmark event was followed in 1993 by the sale of The Star of Happiness, a modified rectangular brilliant 100.36 carat diamond that fetched 17.8 million CHF (approximately $118,397 per carat). Then in 1995 came the Star of the Season, a 101.10 carat D color, Internally Flawless pear-shaped diamond that sold for $16.4 million and held the per-carat price record for nearly 15 years.
Each appearance of a 100 carat D-Flawless or Internally Flawless diamond at auction becomes an international news story. Such diamonds are exceedingly rare with less than 0.5% of all stones over one carat submitted to the GIA annually meet these standards. Sotheby’s continues to lead the market in offering these unparalleled treasures to collectors around the globe.
118.28 Carat Oval Brilliant-Cut Diamond, $30.8 million
In 2013, Sotheby’s sold a spectacular 118.28 carat oval brilliant-cut diamond for 238,680,000 HKD ($30.8 million), making it the most expensive 100 carat diamond Sotheby’s has sold. Graded D color, Flawless clarity, Type IIa with Excellent Polish and Symmetry, this unmounted diamond originated from a 299 carat rough discovered in Southern Africa in 2011. The gem was described as having a “watery” transparency and exceptional brilliance.
100.20 Carat Emerald Cut Diamond
A truly exceptional 100.20 carat emerald-cut diamond is currently available through Sotheby’s Private Sales. This D color, Internally Flawless Type IIa diamond is mounted in platinum and inscribed with its carat weight on the inner shank. Its elegant, elongated form emphasizes the stone’s remarkable clarity and icy brilliance. Offering a unique opportunity to own one of the world’s rarest diamonds, collectors and connoisseurs can inquire directly through Sotheby’s for a discreet and personalized opportunity to acquire one of the world’s rarest diamonds.
THE VICTOR 10239, $15.7 million
In 2020, Sotheby's sold The Victor 10239, an oval 102.39 carat D color, Flawless, Type IIa diamond with excellent polish and symmetry. Originating from a 271 carat rough recovered from Canada’s Victor Mine, this masterpiece was cut by Diacore and sold for 121,562,000 HKD ($15.7 million).
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 for 14.5 million CHF ($13.3 million). Weighing 100.09 carats, this Fancy Vivid Yellow, VVS2 clarity, modified cushion-cut diamond is one of the largest yellow diamonds ever sold. Its fire and brilliance have earned it a place in Ian Balfour’s Famous Diamonds.
Juno Diamond, $13.0 million
In 2022, Sotheby's sold the Juno Diamond, a 101.41 carat D color, Internally Flawless, Type IIa pear-shaped diamond for $13.0 million. Its price reflects its rarity, purity, and exceptional craftsmanship.
The Sun Drop Diamond (The Lady Dalal), $12.4 million
Sold in 2011 for 11.3 million CHF ($12.4 million), The Sun Drop Diamond is a 110.03 carat Fancy Vivid Yellow pear-shaped diamond, renamed The Lady Dalal after the sale. Exhibited at London’s Natural History Museum, this diamond’s color results from nitrogen atoms incorporated into its crystal structure 1–3 billion years ago.
The Key 10138, $12.2 million
In 2021, Sotheby’s sold The Key 10138, a 101.38 carat D color, Flawless, Type IIa pear-shaped diamond for 95.1 million HKD ($12.2 million). It was the second-largest pear-shaped diamond ever offered publicly and set a record for the most expensive jewel 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.
In 2018, Sotheby’s sold a 102.34 carat round brilliant-cut D color, Flawless, Type IIa diamond—making it the largest of its kind graded by the GIA. Mined in Botswana and originally weighing 425.40 carats, it was cut over six months into 25 diamonds by Diacore. The price remains private but set a new high per carat for colorless diamonds.
100 Carat Diamond Price
The value of a 100 carat diamond is primarily determined by the Four Cs—cut, color, clarity, and carat weight—with exceptional stones fetching $12 million to over $30 million at Sotheby’s. Because of their rarity and appeal to a highly exclusive market, price forecasting can be difficult. There are only about 2,800 billionaires worldwide and 426,000 ultra-high-net-worth individuals with assets over $30 million. The number of potential buyers is small, but when multiple collectors are interested, bidding can soar above expected values.
From the legendary Golconda diamonds to today’s record-setting auctions and private sales, Sotheby’s has maintained its role at the pinnacle of the global diamond market. The enduring allure of 100 carat diamonds lies not only in their sheer scale and rarity but in the exquisite craftsmanship and geological wonder they embody. Whether sold under the gavel or through an intimate private transaction, these stones continue to captivate collectors, connoisseurs, and dreamers alike—each one a frozen moment of beauty millions of years in the making.
Advantages to Buying Diamonds on the Secondary Market
1. Access
Sotheby’s provides exclusive access to a curated selection of diamond jewelry from the world’s most prestigious Maison's, including Van Cleef & Arpels, Cartier, Tiffany & Co and more. Clients can find top quality diamonds from one carat to more than twenty carats from top brands and bespoke creations. Our jewelry specialists work closely with collectors worldwide to source coveted diamond jewelry to provide exclusive access to the rarest and most desirable diamond jewelry.
2. Flexibility
Sotheby’s offers unique access to a wide selection of signed and unsigned diamond jewelry available at auction around the world. We also offer diamond jewelry for immediate purchase and allow easy side-by-side comparison of top brands and unsigned diamonds. We also offer a bespoke concierge service to help source unique one-of-a-kind diamond jewelry.
3. Value
The secondary market is an attractive alternative for purchasing diamond jewelry since you can realize more value compared to traditional retailers. Top brands and jewelry retailers add a material premium to cover manufacturing and other fixed costs that are not reflected in the prices at Sotheby’s. It’s possible to purchase classic diamond jewelry from top brands including Tiffany & Co., Cartier and Harry Winston at less than half of the original retail price. These pieces also often include the original packaging and certificates. Sotheby’s Jewelry specialists also inspect every item before accepting it for sale.
4. Discovery
One of the greatest advantages of shopping in a global luxury marketplace is the opportunity to discover rare and unique diamond jewelry pieces that are no longer available through traditional retail channels. Our curated selection of diamond jewelry is continuously refreshed, ensuring that you’ll always find something new and exclusive to build your collection.
Buy and Sell 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 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.
