The Portuguese Diamond: A Study of Magnificence

The Portuguese Diamond: A Study of Magnificence

The Portuguese Diamond

The Portuguese Diamond // Chip Clark digitally enhanced by SquareMoose / Smithsonian Institute


The Portuguese Diamond, renowned for its striking brilliance and size, is a gem that has enchanted gemologists and jewelry enthusiasts for generations. This article delves into the fascinating world of this unique diamond, focusing on its significant owners, size, carat, geological details, and value.


History and Significant Owners

Peggy Hopkins Joyce

Peggy Hopkins Joyce // Raymond Perry Rogers Nielson


The diamond's name originates from its ownership by the Portuguese Royal Family in the early 20th century. Its previous history remains uncertain, with many speculating that it was mined in the 18th century.

The diamond, originally nearly 150-carats, was part of the Portuguese Crown Jewels, and it was later acquired by Black, Starr & Frost, a prominent American jewelry company, who re-cut the diamond to its 127.01-carat Asscher cut shape. Subsequently, the diamond was sold in 1928 to Peggy Hopkins Joyce, a famous actress and Ziegfeld Follies starlet, known for her jewelry collection, who traded a $350,000 pearl necklace and $23,000 in cash for the piece.

In 1951, Harry Winston purchased the Portuguese Diamond from Peggy Hopkins Joyce, and it subsequently embarked on a journey across the U.S., becoming a central piece in Winston's "Court of Jewels" exhibit. Several years later, in 1963, the Smithsonian Institution obtained the diamond from Mr. Winston, trading 3,800 carats of smaller diamonds for the esteemed gem. Today, the magnificent Portuguese Diamond can be admired in the Gem Gallery at the National Museum of Natural History, where it stands as a testament to its storied past and exceptional beauty.


Size and Carat


The Portuguese Diamond // Wikimedia Commons


The Portuguese Diamond is an impressive specimen, weighing 127.01-carats. Its large size and unique cut contribute to its remarkable beauty and value. The gem is a faceted round brilliant cut, designed to maximize the diamond's fire and brilliance.


Geological Detail


THe Portuguese Diamond

The Portuguese Diamond // Wikimedia Commons


The diamond's geological characteristics contribute to its rare beauty. It is classified as a Type IIa diamond, meaning it contains very few or no nitrogen atoms in its structure. This category of diamonds is known to be the most chemically pure and often displays exceptional optical transparency.

The Portuguese Diamond's color grading is unique, displaying a faint blue hue. This hue is a result of minute traces of boron within the diamond's crystal lattice structure. The gem's clarity is also remarkable, contributing to its stunning brilliance. 

When subjected to ultraviolet light, this diamond exhibits a bright blue glow, a remarkable occurrence known as fluorescence. In 1997, the Gemological Institute of America (GIA) classified the diamond's color as M, indicating a faint brownish-yellow hue, and its clarity as VS-1, meaning very slightly included, with a pronounced blue fluorescence. This intense fluorescence creates an apparent cloudiness within the stone, visible even under daylight or incandescent light. Interestingly, without this fluorescence, the diamond would present a slightly yellowish appearance.



Estimating the exact value of the Portuguese Diamond is challenging due to its rich history, size, and rarity. However, based on comparable diamonds and considering its provenance, the value can be speculated to be in the tens of millions of dollars.

While its monetary value is immense, the diamond's historical and cultural significance transcends any price tag. Its association with the Portuguese Royal Family and prominent collectors in the American jewelry world adds layers of intrigue and value to the gem.



The Portuguese Diamond stands as a symbol of beauty, rarity, and elegance. Its mesmerizing characteristics, including its impressive size, flawless clarity, and faint blue hue, make it one of the world's most renowned diamonds.

From the hands of royalty to prominent American collectors, the Portuguese Diamond's journey through history adds to its allure. Its geological uniqueness speaks of the Earth's incredible ability to create something so pure and beautiful.

The Portuguese Diamond is more than a gem; it is a testament to human fascination with the extraordinary. Its place in the Smithsonian Institution ensures that this incredible piece of history will continue to captivate and inspire generations to come.


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