Diamond History

Discovered in Brazil

The rough crystal that became the Moussaieff Red was discovered in Brazil during the 1990s.

GIA reports that the stone was found by a Brazilian farmer and originally weighed approximately 13.90 carats.

More recent GIA research identifies its origin more specifically with the Rio Abaeté area of Minas Gerais, Brazil.

An Alluvial Diamond

The Moussaieff Red is associated with an alluvial deposit, meaning the diamond was recovered from sediments rather than directly from its original volcanic host rock.

Over immense spans of geological time, erosion can transport diamonds away from their original source and concentrate them in river gravels and other sedimentary deposits.

From a 13.90-Carat Rough Crystal

The original rough diamond weighed approximately 13.90 carats.

Cutting such a rare colored diamond requires a very different strategy from cutting a conventional colorless diamond.

The primary objective is not simply to maximize brilliance or preserve weight. The cutter must also orient and shape the stone so that its natural color appears as strong and evenly distributed as possible when viewed face-up.

In the case of the Moussaieff Red, more than half of the original rough weight was sacrificed in order to produce the exceptional finished gemstone.

Cut by William Goldberg Diamond Corporation

The rare Brazilian rough was acquired and cut by the William Goldberg Diamond Corporation of New York.

William Goldberg built an international reputation for handling exceptional large diamonds and important fancy-color stones.

The cutting team transformed the 13.90-carat rough crystal into the remarkable 5.11-carat finished diamond known today.

A Modified Triangular Brilliant

The Moussaieff Red is fashioned as a modified triangular brilliant, often referred to in the trade as a trilliant.

This shape was chosen not merely for appearance. Fancy-color diamonds are often cut with modified brilliant facet arrangements designed to reflect light through the stone in ways that intensify the apparent body color.

The finished shape gives the Moussaieff Red its recognizable broad triangular profile while helping emphasize its extraordinary red coloration.

The Rarity of a True Fancy Red Diamond

Natural red diamonds occupy one of the rarest categories in the entire diamond-color spectrum.

Many diamonds that appear red contain a secondary modifying color and receive grades such as Fancy purplish red or Fancy orangy red.

The Moussaieff Red is extraordinary because GIA graded its hue simply as Fancy Red.

In other words, no secondary hue is required to describe its dominant color.

Why "Fancy Red" Is Different

Most fancy-color diamonds can receive a range of saturation grades such as Fancy Light, Fancy, Fancy Intense, Fancy Deep or Fancy Vivid.

Red diamonds are treated differently in GIA's color-grading system.

For an unmodified red diamond, the designation is simply Fancy Red.

This reflects the extremely narrow range of tone and saturation in which a diamond can exhibit a true unmodified red appearance.

What Causes Red Color in a Diamond?

Unlike blue diamonds, whose color is often associated with trace boron, or yellow diamonds, whose color is commonly associated with nitrogen, the origin of red coloration is more closely related to structural deformation within the diamond crystal.

During the diamond's geological history, enormous stresses can alter the arrangement of carbon atoms within the crystal lattice.

These atomic-scale distortions affect the way the diamond absorbs visible light and can produce pink or, in exceptionally rare cases, red coloration.

Acquired by Moussaieff Jewellers

The Red Shield was eventually acquired by Moussaieff Jewellers, the internationally known luxury jewelry house.

Following the acquisition, the stone became known as the Moussaieff Red Diamond.

The new name permanently linked the remarkable gemstone with the Moussaieff name and helped establish its identity among the world's best-known fancy-color diamonds.

The Splendor of Diamonds Exhibition

In 2003, the Moussaieff Red was selected for one of the most important exhibitions of famous modern diamonds.

The Smithsonian National Museum of Natural History assembled seven exceptionally rare diamonds for The Splendor of Diamonds exhibition in Washington, D.C.

The exhibition opened on June 27, 2003 and brought together diamonds representing an extraordinary range of natural colors.

Among the World's Rarest Colored Diamonds

The Moussaieff Red appeared alongside several other extraordinary diamonds, including:

De Beers Millennium Star
The Allnatt
Steinmetz Pink
Heart of Eternity
Pumpkin Diamond
Ocean Dream

Although the 5.11-carat Moussaieff Red was physically smaller than most of the other diamonds on display, its pure red color made it one of the rarest stones in the entire exhibition.

Why 5.11 Carats Is Extraordinary

A five-carat diamond may seem small when compared with famous stones weighing hundreds of carats, but size must be considered in relation to color rarity.

True Fancy Red diamonds are typically very small.

GIA's modern research into publicly documented Fancy Red diamonds shows that only a tiny fraction exceed two carats.

At 5.11 carats, the Moussaieff Red is extraordinarily large for a diamond possessing an unmodified Fancy Red color grade.

The Largest Publicly Documented Fancy Red Diamond

GIA research published in 2025 continues to identify the Moussaieff Red as the largest publicly documented diamond with an unmodified Fancy Red GIA color grade.

The 5.11-carat Moussaieff Red ranks ahead of other publicly documented Fancy Red diamonds such as the 2.33-carat Winston Red and the 2.11-carat Argyle Everglow.

This distinction reinforces the Moussaieff Red's importance not only as a famous gemstone but also as an exceptional gemological specimen.

A Note on Clarity

Older descriptions of the Moussaieff Red have sometimes referred to the diamond as internally flawless.

However, GIA's 2025 published table of publicly documented Fancy Red diamonds lists the Moussaieff Red's clarity as unknown.

For that reason, DiamondAvenue does not assign a specific clarity grade to the stone here.

Why the Moussaieff Red Diamond Is Famous

The Moussaieff Red is famous not because it is one of the world's largest diamonds overall, but because it represents one of the rarest combinations possible in a natural diamond.

Its color is an unmodified Fancy Red, a classification achieved by only a very small number of natural diamonds.

Its 5.11-carat weight is exceptional for a pure red diamond, while its modified triangular brilliant cut gives the stone a distinctive and immediately recognizable appearance.

Its Brazilian origin, transformation from a 13.90-carat rough crystal, association with William Goldberg, acquisition by Moussaieff Jewellers and inclusion in the Smithsonian's The Splendor of Diamonds exhibition all contribute to its international fame.

Legacy of the Moussaieff Red

The Moussaieff Red demonstrates that rarity in diamonds is not measured by size alone.

A five-carat diamond may appear modest beside famous stones weighing hundreds of carats, but an unmodified natural Fancy Red color is so exceptionally rare that the Moussaieff Red occupies a category of its own.

From a 13.90-carat Brazilian rough crystal to a precisely fashioned 5.11-carat red gem, the stone represents a remarkable combination of geological rarity and skilled diamond cutting.

Its inclusion in the Smithsonian's 2003 exhibition and its continuing status in GIA research have secured the Moussaieff Red's place among the most important colored diamonds ever documented.