The Blue Heart Diamond: A Jewel to Admire

Origin: Premier Mines, South Africa

Initial weight: 100.5 carats

Weight after processing: 30.62ct

Shape: Heart-shaped

Cut: brilliant-cut

Color: Light grey-blue

Clarity Grade: VS-2

Creator: Atanik Eknayan, Harry Winston, Inc.

Date Created: 1909/1964

The Blue Heart Diamond was discovered at Premier Mines in South Africa in 1908. At one point, there was controversy surrounding the real origin, with some arguing that the diamond might have come from India. The Blue Heart Diamond weighed a whopping 100.5 carats at its discovery. Subsequent cutting and polishing activities would later reduce that weight to 30.62 carats. As many similar gigantic diamonds find, the Blue Heart Diamond began to generate media attention as soon as it was discovered.

In 1909, the Premier Transvaal Diamond Mining Company purchased the diamond, and a year later, the cutting and processing work began. The cutting work was entrusted to a Paris-based French jeweler, Atanik Eknayan. Mr. Eknayan carefully cut and faceted the diamond into the heart-shaped stone we know today. The Blue Heart Diamond was set as the center stone of a lily-of-the-valley ornament necklace in the same year. A year later, the French jeweler Pierre Cartier purchased the gemstone and sold it to the Unzue family of Argentina. Maria Unzue gifted the diamond to her niece, Angela Gonzalez Alzaga, as a wedding present in 1936.

In 1953, Van Cleef & Arpels acquired the Blue Heart Diamond and reset it into a pendant. The elegant pendant also featured other unique gems, including a 2.05-carat pink diamond, making it one of the most beautiful necklaces of the time. Later that year, the $300,000 necklace would be sold to a Swiss industrialist, Baron Hans Heinrich Thyssen-Bornemisza.

Afterward, the diamond changed many hands, mostly under reputable jewelry dealers' ownership. Harry Winston acquired the gem in 1959 from Nina Dyer, an ex-wife to Mr. Thyssen-Bornemisza. Harry Winston then mounted the diamond on a ring before selling it to Marjorie Merriweather Post, the American socialite who founded General Foods Inc. in 1960. Mrs. Post was the last private owner ever to have handled the Blue Heart Diamond. She eventually gifted the gemstone to the Smithsonian Institution in Washington, D.C., in 1964. The diamond continues to remain there to date.

In 1997, the Gemological Institute of America graded the stone as a Natural Fancy Blue Color Diamond. After grading, the diamond was assigned a clarity grade of VS2 (very slightly included), making it one of the world’s largest flawless diamonds.

The name “Blue Heart” was inspired by the diamond’s rare deep-blue color and heart-shaped cut. It is arguably one of the world’s prettiest blue diamonds and, coupled with its heart-shaped cut, is also one of the rarest. The Blue Heart Diamond is often referred to as Unzue, apparently in tribute to Mrs. Unzue, the Argentinean woman who owned the diamond for a staggering 43 years after purchasing it from Pierre Cartier just two years after its discovery.

Blue Heart is also often referred to as "Eugenie Blue.’’ It is rather unclear why the diamond is named after the French Empress Eugenie, whose reign had ended long before the diamond was discovered. The only French link to the diamond is that it was cut and faceted by Atanik Ekyanan, a link seemingly unrelated to the empress.

In terms of its size, the Blue Heart Diamond is believed to be two-thirds the size of another significant diamond found, the Hope Diamond.

When Harry Winston acquired the Blue Heart Diamond, they mounted the stone in its present platinum ring setting. The choice of the ring setting was appropriate as it added more brilliance to the stone, given that it was already sparkly. Winston reckoned that a platinum ring would accentuate the diamond’s deep blue color, enhancing its fire and brilliance. The diamond’s blue color is attributed to the trace amounts of boron within the stone’s crystal structure, replacing several carbon atoms.

The Blue Heart Diamond is not the only gemstone in the National Gem Collection. The collection houses some of the world’s popular gems, such as the Hope Diamond. However, the Blue Heart is outstanding due to its lively blue color and fancy heart shape.

The Blue Heart Diamond enjoys the coveted distinction as the world’s largest heart-shaped blue diamond. The gemstone has held that position since it was cut and faceted in 1909, and, considering how difficult it is to obtain large blue diamonds, this gemstone is likely to continue holding on to the title. The intricate process involved in the cutting and faceting heart-shaped diamonds implies that there is only a handful of diamonds with such attributes, a factor that adds an extra layer of rarity and uniqueness to the Blue Heart.

There are only three other famous large, heart-shaped blue diamonds in the world. The first is the Heart of Eternity, weighing 27.64 carats, exhibited at London’s Millennium Dome in 2000. Next is the iconic 203.04-carat Millennium Star, while the third is the 5.46-carat heart-shaped Marie Antoinette diamond. Blue Heart ranks as the world’s 11th largest diamond overall.

Additionally, the Blue Heart Diamond has earned itself a place among the Type IIb group of diamonds, including only naturally-colored blue diamonds. It is important to note that the occurrence of naturally-colored blue diamonds is less than 0.1% of all the other natural diamonds, making them the rarest and some of the most expensive stones available. Diamonds that fall under the Type IIb category either contain no nitrogen at all or contain nitrogen in their crystals only to such an extent that cannot be detected even by the most sophisticated gemological equipment.

The Type IIb category of diamonds is contrasted with the Type IIa category because diamonds in the latter category are free of nitrogen and other chemical impurities. About 1–2% of the world’s naturally-occurring diamonds belong to the Type IIa category. Unfortunately, Type IIb diamonds, to which category Blue Heart belongs, contain traces of impurities such as boron. As has already been pointed out, the boron element in the Blue Heart’s crystal structure accounts for the diamond’s deep blue color—this is so because boron changes the diamond’s light absorption spectrum significantly. Besides, the presence of boron in the Blue Heart Diamond also makes the gemstone a semiconductor of electricity.

Origin Shrouded in Mystery

There have occurred instances when doubts have been expressed with regard to the exact origin of the Blue Heart Diamond. Some people were of the view that the diamond might have originated in India because, around the time the gemstone was supposedly discovered, India was a major world producer of rough diamonds.

However, these doubts have since been cleared by National Museum of Natural History researchers. The researchers argued that most mining activities in India had ceased by the dawn of the 20th century. Moreover, operations had already been abandoned in India’s most diamond-productive region of the Eastern Deccan Plateau.

To further demystify the theory of the diamond’s being of Indian origin, researchers at the Natural History Museum dug into the archives of De Beers, where they unearthed evidence that suggested that the Blue Heart was discovered at Premier Mines in South Africa. Apart from uncovering the origin, the researchers also established that the diamond was discovered in November 1908 and weighed 100.5 carats.

Changing Hands

The Blue Heart Diamond is one such gemstone that has fallen under the ownership of many entities before finding its permanent home at the National Gem Collection. Though its history began in South Africa, Blue Heart traversed the world, having been owned by both private entities and jewelry companies.

The most notable private entities to have owned the diamond include the Unzue family, Hans Heinrich Thyssen-Bornemisza family, and Marjorie Merriweather Post. On the other hand, some prominent jewelers who acquired the Blue Heart include Harry Winston and Pierre Cartier. However, the Unzue family owned the diamond for the longest time—a record 43 years. Given this fact, it is no wonder the gemstone is often called Unzue Diamond.

Current Location

The histories of the world’s most iconic diamonds usually assume a similar trajectory. First, the diamond is discovered, then popularized, and finally sold to a royal ruler or auctioned to private jewelers. The Blue Heart Diamond has witnessed somewhat similar circumstances.

But despite its rarity, the final owner of the diamond, Mrs. Post, appears not to have attached so much economic importance to the diamond. She eventually donated the stone to the National Museum of Natural History of the Smithsonian Institution in Washington, DC. The diamond is displayed in the Janet-Annenberg Hooker Hall of Geology, Gems & Minerals.

The Blue Heart Diamond remains one of the world’s most cherished gems, and although it is not the world’s largest diamond ever discovered, it is the rarest in terms of its color and shape. This factor alone explains why the Smithsonian Institution is keen on retaining the diamond as part of its vast collection of precious and unique gemstones.