This is the Rarest Natural Diamond Color of Them All

Meet the red diamond.

By |
A pear shaped red diamond from Leibish

There are few things on Earth so rare that scientists lack the ability to study them properly. Take ball lightning as an example. Ball lightning is a very rare phenomenon described as spherical, exploding balls of electricity—like something from science fiction. It is so rare that it doesn’t exist enough for scientists to study and fully understand. The same can be said for red diamonds.

Natural diamonds, as a whole, are among the rarest substances on earth, and when we break out the category of natural color diamonds, we find that they are even rarer. In fact, according to the GIA, only 0.4% of all natural diamonds graded in the last twenty years have been fancy colors. Among all those fancy color diamonds, red is the rarest color. They are so rare that less than thirty true red natural diamonds are known to exist. 

red diamond
A radiant cut red diamond mounted in a diamond ring from Leibish.

A diamond is a crystalline form of pure carbon formed under extreme conditions within the Earth up to three billion years ago. Elements other than carbon or natural radiation introduced during formation can alter a natural diamond from a colorless crystal to one that exhibits almost any color of the rainbow. For instance, natural radiation within the earth can cause green diamonds; boron can cause blue diamonds. On the other hand, red diamonds are not thought to be caused by foreign elements like other diamond colors.

Instead, scientists believe red diamonds are caused by an extreme version of crystal lattice distortion—the same thing that makes pink diamonds pink. This distortion is created naturally, deep in the earth, by extreme heat and pressure in every direction after the stone was formed. The extra heat and pressure can change the position of the carbon atoms inside the diamond, causing them to reflect pink or—in extreme cases—red light. Although most believe this is what causes these diamonds to have their color, the phenomenon is so rare that scientists cannot study it enough completely.

red diamond
Leela Gera Red Princess – 1.01 Fancy Purplish Red (One of the rarest Natural Red Princess-shaped diamonds ever found.)

As these diamonds are so rare, they have never been found in large sizes. Even though finding colorless diamonds is also rare, we occasionally find sizes 100 carats or more. With red diamonds, however, the largest one in existence is only 5.11 carats, named The Moussaieff Red. Discovered in the 1990s in the Minas Gerais region of Brazil, a source of natural color diamonds for hundreds of years, The Moussaieff Red was 13.90 carats in its rough form.

Following negotiations with the man who discovered the diamond, it was eventually purchased by legendary diamond cutter William Goldberg. After much study, analysis and planning, Goldberg eventually cut the rough diamond into the 5.11 carat triangular brilliant cut we know today, and it officially became the largest fancy red diamond in history. In 2001, Goldberg sold the diamond to the famous London jeweler Shlomo Moussaieff, from whom it gets its name. The reported sale at the time was $8 million, a bargain considering the priceless nature of the stone today. The Moussaieff Red remains in the hands of Moussaieff Jewelers and has since had multiple stints at museum exhibits, including the famous “Splendour of Diamonds” exhibition at the Smithsonian in 2003 (considered one of the most significant diamond exhibitions of all time). 

red diamond
The Moussaieff Red Diamond

Like most other fancy color diamonds, these diamonds can be found in one pure color, fancy red, or with secondary hues, which include purplish, brownish and orangey; for example, in a ‘fancy orangey red’ diamond, red is the dominant color, but orange is the secondary color. Unlike most other color diamond color possibilities, red cannot be a secondary color. Most natural color diamonds also come in several intensity levels, such as intense, vivid or light. An example of this could be ‘fancy vivid pink’ or ‘fancy light yellow.’ These diamonds, however, only come in one intensity level, fancy red. For these reasons, ‘fancy red’ alone is the rarest and, therefore, the most valuable.

red diamond
A radiant cut red diamond that was featured in the final Argyle Diamond Tender.

Since so few exist, red diamonds—even those with modifying colors—do not come to market very often. However, when they do, they command prices of easily more than $1 million per carat, far more than almost any other type of diamond. In 2022, Heritage auctions sold a 1.21 carat fancy orangy red diamond for over $1.2 million per carat, a massive sum for a diamond of that size, especially considering it has a modifying color. Because of their great value and the history of their value continuously rising, red diamonds are most often purchased by investors.

While most of us may never be fortunate enough to own one of these stones, one of the largest and most beautiful red diamonds ever discovered is available for nearly anyone’s gaze. The 5.03 carat round brilliant cut De Young Red is the third-largest diamond of its kind in existence and sits in the permanent collection of the Smithsonian Museum in Washington, D.C. A visit to their famous gem exhibit to see the De Young Red and the rest of their incredible diamond collection deserves a spot at the top of your D.C. itinerary.