Diamonds are among the most valuable gemstones in the world, prized for their fire, brilliance, and sparkle. The value of a diamond depends on several factors, most notably its weight in carats, color, clarity, and cut. Larger diamonds are exponentially more rare and valuable than smaller ones. A 100 carat diamond is extremely large and would command an astronomical price.
What is the price per carat for large diamonds?
Diamonds over 10 carats are considered investment-grade stones and their price per carat increases exponentially with carat weight. The largest diamonds can sell for over $1 million per carat at auction. To estimate the potential value of a 100 carat diamond, we can look at some recent sales of large, high quality diamonds:
- In 2016, a 59.6 carat pink diamond sold for $71 million, or over $1.2 million per carat.
- In 2017, a 163.41 carat D color flawless diamond sold for $33.7 million, or over $200,000 per carat.
- In 2018, Sotheby’s sold a 102.34 carat D color internally flawless diamond for $30.8 million, or over $300,000 per carat.
Based on these sales, a 100 carat top color and clarity diamond could reasonably expect to achieve $100,000 to $300,000+ per carat at auction. This means a 100 carat diamond could sell for $10 million to $30 million+ to the right buyer.
Factors impacting large diamond value
However, it’s important to note that the value of any diamond depends on more than just carat weight. A poorly cut or off-color 100 carat diamond would sell for far less. Here are the key factors impacting value:
Color
Diamond color is graded on a scale from D (colorless) to Z (light yellow/brown). The highest prices are achieved by rare diamonds rated D-F for being colorless to near colorless. As more color is present, values decrease significantly. A 100 carat diamond with a poor K-M color would be worth a fraction of a D color stone of equal weight.
Clarity
Diamond clarity refers to the absence of inclusions and blemishes. Flawless or internally flawless diamonds are the most rare and valuable. Diamonds with more flaws, even if not visible to the naked eye, will decrease the value. While small flaws don’t impact smaller diamonds as much, large diamonds must have exceptional clarity to achieve top auction prices.
Cut
The cut quality of a diamond relates to its proportions, symmetry, and polish. Well-cut diamonds exhibit tremendous brilliance and fire. Poorly cut diamonds can have dull, lifeless areas even with excellent color and clarity grades. Additionally, the cut has a major impact on the weight retained from a rough diamond. A diamond cutter must balance maximizing carat weight without compromising beauty and sparkle.
Source and History
The source and history of a diamond also impact its cachet. Diamonds sourced from famous historic mines or those previously owned by royalty or celebrities can achieve auction prices exceeding market rates. For example, the oval-shaped 59.60 carat “Pink Star” that sold for a record $71 million in 2017 was fancy vivid pink, internally flawless, and had a long history, starting with its discovery in a De Beers mine in 1999.
What is the current world record price per carat for a diamond?
The current record holder for the highest price per carat paid at auction for a diamond is the Blue Moon of Josephine diamond, which sold for over $4 million per carat in 2015. Here are details on this extraordinary stone:
- Carat weight: 12.03 carats
- Color: Fancy Vivid Blue (extremely rare)
- Clarity: Internally Flawless
- Cut: Cushion Modified Brilliant
- Sold for: $48.4 million total, or over $4 million per carat
- Sold by: Sotheby’s Geneva in 2015
- Buyer: Hong Kong billionaire Joseph Lau
The previous record was held by the Graff Pink diamond, which sold for $1.86 million per carat in 2010. The Blue Moon of Josephine shattered that record due to its exceptional color. Vivid blue diamonds of over 10 carats are practically unheard of at auction. While the Blue Moon isn’t the largest diamond ever sold, its perfect color, clarity, and cut make it the highest per carat diamond ever sold.
What is the price differential for various colors and clarities?
Diamond values vary greatly depending on color and clarity grades. Here is a general overview of how these factors impact price per carat for round brilliant cut diamonds:
Color:
| Color Grade | Price per Carat |
|---|---|
| D-F (Colorless) | $12,000 – $15,000+ |
| G-H (Near Colorless) | $9,000 – $12,000 |
| I-J (Near Colorless) | $6,000 – $9,000 |
| K-L (Faint Yellow) | $3,000 – $5,000 |
| M-Z (Light Yellow/Brown) | $1,000 – $3,000 |
As you can see, exceptional D-F color diamonds command premium pricing, with prices dropping off significantly once faint yellow color becomes visible. Intense fancy color diamonds like vivid pinks, blues, and yellows are their own separate category and can achieve prices many times higher than colorless diamonds.
Clarity:
| Clarity Grade | Price per Carat |
|---|---|
| Flawless (FL) | +$20,000+ Premium |
| Internally Flawless (IF) | +$10,000+ Premium |
| Very Very Slightly Included 1 & 2 (VVS1, VVS2) | Baseline |
| Very Slightly Included 1 & 2 (VS1, VS2) | 10-20% Discount |
| Slightly Included 1 & 2 (SI1, SI2) | 20-40% Discount |
| Included 1, 2, 3 (I1, I2, I3) | 40-60% Discount |
Diamonds with no or very minor flaws have significant premiums. Once the inclusions become more visible to the eye, prices start to decrease by significant percentages. An estimated 80% of diamonds on the market are VS clarity or below, making FL and IF diamonds extremely rare and valuable.
How is value impacted by cutting quality?
Well-cut diamonds command premium pricing and can show their quality even without a trained eye. Here are some factors to look for in a well-cut diamond:
- Brightness – Contrast between white and black facets optimizes light return through the crown.
- Fire – Flashes of spectral colors visible as the diamond moves.
- Scintillation – Sparkling as the diamond catches the light.
- Symmetry – Precise placement of facets and outline shape.
- Table percentage – Neither too large or small, ideal is 53% to 63%.
- Girdle thickness – Neither extremely thick or thin.
- Culet – Small or pointed tip at bottom of pavilion.
- Polish – No visible roughness to facets, excellent polish.
Diamonds that are cut too shallow or deep can have subpar brilliance, while off-center tables, skewed facets, or poor symmetry also detract. Obtaining certification from GIA, AGS, or another independent lab helps confirm optimal cut quality.
In general, a well-cut diamond will command premium pricing in the range of 5-15% compared to a fair/poor cut diamond of the same carat weight, color, and clarity. This premium can potentially be higher for larger diamonds, where cutting precision is more challenging.
How large was the biggest rough diamond ever found?
The largest rough diamond ever discovered is the 3,106-carat Cullinan diamond found in South Africa in 1905. It was found at the Premier No. 2 mine near Pretoria, South Africa and weighed a massive 1.33 pounds!
The Cullinan is the largest gem-quality rough diamond ever found, but larger non-gem quality crystals have been found as well, such as the Sergio diamond rough (3,167 carats) discovered in Brazil in 2018. Here are more details on the Cullinan rough diamond:
- Discovered in 1905 in Premier Mine, South Africa
- Original size: 3,106 carats (1.33 pounds)
- Color: D – near colorless
- Clarity: Slightly included
- Cut into 9 major diamonds + 96 smaller ones
- Largest polished stones are Cullinan I & II (530 and 317 carats)
The Cullinan rough diamond was purchased by the Transvaal government and then gifted to King Edward VII. It was cut by Asschers of Amsterdam and remains the largest gem-quality rough diamond ever discovered. The subsequent high quality polished diamonds make the Cullinan one of the most famous diamonds in history.
What is the largest polished diamond in the world?
The largest faceted diamond in the world is the Golden Jubilee Diamond, weighing 545.67 carats. It surpassed the long-held record of the Cullinan I diamond (530.2 carats). The Golden Jubilee was discovered in 1985 in the Premier Mine in South Africa as a 755.5 carat brown diamond. Here are more facts about this phenomenal stone:
- Original rough weight: 755.5 carats
- Cut weight: 545.67 carats
- Color: Fancy Yellow-Brown
- Clarity: VS2
- Cut: Fire Rose Cushion
- Dimensions: 60.6mm x 31.90mm x 22.47mm
- Cut by Gabi Tolkowsky in 1990
The Golden Jubilee was presented to the King of Thailand in 1997 for his 50th coronation anniversary, which is how it got its name. It is the largest cut and polished diamond in the world. While brown diamonds are less rare than colorless, the Golden Jubilee’s size, color, and flawless polish make it a truly unique gem.
What is the largest diamond ever graded by the GIA?
The GIA (Gemological Institute of America) has graded and certified some of the most important diamonds in history. The largest diamond ever graded by the GIA is the Deepdene diamond. Here are the facts on this massive stone:
- Weight: 104.52 carats
- Dimensions: 29.6mm x 21.27mm x 17.14mm
- Cut: Emerald
- Color: I
- Clarity: VS2
- Origin: South Africa
- Date Graded: April 2021
The 104.52 carat Deepdene diamond was named after the famous British country house museum where it was displayed for years. It recently sold at a Christie’s auction for over $15 million.
While the Deepdene is the largest diamond certified by the GIA in terms of carat weight, it doesn’t have the largest dimensions graded. That record belongs to the Incomparable Diamond, weighing 407.48 carats but with massive dimensions of 53.90mm x 35.19mm x 28.89mm. This makes it the largest internally flawless diamond graded by the GIA.
What are the largest diamonds found in recent years?
Several phenomenal diamonds have been unearthed in just the last 5 years. Here are some of the largest and most notable:
- Sewelo Diamond – 1,758 carats, discovered in 2019 in Botswana by Lucapa Diamond Company. It is the 2nd largest diamond ever found.
- Lesedi La Rona – 1,109 carats, discovered in 2015 in Botswana by the Lucara Diamond Corp. It was sold for $53 million in 2017.
- Constellation Diamond – 813 carats, discovered in 2015 in Botswana’s Karowe mine. It was sold for $63.1 million in 2016.
- Graff Lesedi La Rona – 302.37 carats, this diamond was cut from the 1,109 carat rough Lesedi La Rona diamond in 2017.
- Alrosa Diamond – 222.09 carats, the largest diamond ever mined in Russia, discovered in 2017.
These mammoth diamonds were found relatively recently compared to famous diamonds like the Cullinan or Koh-I-Noor, which were unearthed over 100 years ago. Modern diamond mining technology and prospecting techniques continue yielding spectacular results, including seven of the ten largest rough diamonds ever discovered found just in the last 20 years.
Conclusion
In summary, valuing a 100 carat rough diamond depends heavily on its shape, color, clarity, and source. Based on recent auction sales, a top D color, internally flawless diamond could potentially achieve over $3 million per carat if cut to perfection. That would place the value of a 100 carat diamond in the range of $300+ million. Even with imperfections, a 100 carat stone would likely command tens of millions.
While few rough diamonds over 100 carats are ever discovered, the ones that are can end up as miracles of nature. The quality of the stone and the precision of the cutting will determine just how breathtaking the final result will be. In the right hands, a 100 carat rough diamond could yield a polished gem that enters the history books as one of the most perfect and valuable diamonds the world has ever seen.