Said to be one of the most perfectly cut diamonds in the world, the seldom-seen 125.35-carat Jonker I Diamond is now headlining a special exhibition at the Natural History Museum of Los Angeles County (NHM).

Titled "100 Carats: Icons of the Gem World," the presentation features more than two dozen gems that have at least two things in common: Each weighs more than 100 carats and each represents the finest example of its type. The exhibition was assembled by the NHM in collaboration with Robert Procop Exceptional Jewels and runs through April 21, 2024.

The Jonker I Diamond is the largest stone cut from the 726-carat Jonker Diamond, which was the fourth-largest rough diamond in the world when it was found in 1934.

According to the NHM, the historic gem has passed through the hands of global royalty and Hollywood stars, but has not been on display at a museum for more than eight decades. In fact, the public has not seen this diamond since it was bought by a private collector in 1977.

Now, owner Ibrahim Al-Rashid has lent the Jonker I Diamond to NHM for display in this exhibition.

“The Jonker is one of the largest and most famous diamonds ever unearthed,” said Al-Rashid, who is also chairman of Miami-based Limestone Asset Management. “Its beauty and history are compelling. I'm grateful to have it on display for viewers to enjoy for the first time in many decades.”

In addition to the Jonker I Diamond, the gemstones on display in the NHM's Hixon Gem Vault include the following:

The Northern Light beryl (103.30 carats)
The Great White Emerald goshenite (168.20)
The Crown of Colombia emerald (241.04)
The Imperial tourmaline (111.09)
The Blue Star aquamarine (108.29)
The Magnificent paraiba (106.20)
Pride of Sri Lanka, The Healing Blue sapphire (186.82)
The Miracle sapphire (100.06)
The Scepter sapphire (127.30)
The Eastern Star sapphire (177.91)
The Princess Pink sapphire (109.82)
The Scarlet Red rubellite (112.68)
The Ukrainian Flag topaz (153.27)

“The show is a once-in-a-lifetime event,” said Dr. Aaron Celestian, NHM’s curator of mineral sciences. “The rarity of these gems cannot be overstated. Visitors will be able to see tremendous examples of gemstones in a rainbow of vivid colors that have been expertly cut to display their remarkable brilliance. I am thrilled that we’ve been able to bring these giant gems together for the first time.”

The Jonker Diamond has a wild backstory that includes a possible connection to the 3,106-carat Cullinan Diamond, the largest diamond ever unearthed.

On January 17, 1934, a rough diamond the size of a hen’s egg was pulled from a bucket of gravel at the Elandsfontein claim, 4.8 kilometers south of the Premier Mine in South Africa. The massive 726-carat rough diamond with a frosty ice-white color would take on the surname of Jacob Jonker, the 62-year-old digger who owned the claim.

Diamond experts speculated whether the 63.5mm x 31.75mm Jonker and the 3,106-carat Cullinan Diamond had once been conjoined, as their respective cleaved faces seemed to match up perfectly. The Cullinan Diamond had been discovered at the nearby Premier Mine 19 years earlier.

The Jonker rough was acquired by De Beers chairman Sir Ernest Oppenheimer and subsequently caught the attention of diamond dealer Harry Winston, who purchased the rough stone in 1935 for £75,000, the equivalent of £6.7 million ($8.5 million) today.

The Jonker diamond earned celebrity status when it was displayed during the Silver Jubilee Celebrations of the Coronation of King George V and Queen Mary in May of that same year.

The next year, Winston contracted Lazare Kaplan to cut 13 finished gems from the original rough. The Jonker finished diamonds were each named with a Roman numeral, in size order. The largest was the Jonker I at 142.90 carats and the smallest was the Jonker XIII at 3.53 carats. The Jonker I was later re-cut to eliminate flaws and improve its brilliance. The new-and-improved version weighed 125.35 carats.

Please check out the five-minute NHM video, below, which highlights many of the beautiful gemstones in the exhibit, with expert commentary from Celestian, jewelry designer Robert Procop and former president of the Gemological Institute of America Bill Boyajian.

Credit: Image of Jonker I Diamond, photo courtesy of the Natural History Museum of Los Angeles County.