The History of One of the World’s Rarest Diamonds

How the DeYoung Red was acquired as part of an estate jewelry collection in which it was wrongly identified as a garnet, but subsequently identified to be a rare red diamond?

The DeYoung Red diamond was in the possession of Sidney DeYoung, a jeweler from Boston for quite a long time. The stone had been acquired by his establishment as part of a collection of estate jewelry in which it was wrongly identified as a garnet. The item that included the stone had been labeled as a garnet hat pin. But one day, Sidney DeYoung happened to examine the garnet hat pin a little more closely. He noticed the so-called garnet just didn’t look quite like a garnet. Moreover, he observed that for an old stone, it was remarkably clean and wasn’t scratched up. This observation aroused his suspicions, and he took the stone for testing by a gem-testing laboratory. His suspicions were confirmed, and it turned out that the so-called garnet was in fact not a garnet, but a red diamond, the 3rd largest in the world.

Sidney DeYoung donates the DeYoung Red diamond to the Smithsonian’s National Museum of Natural History in 1987, to enrich the National Gem and Mineral Collection

Sidney DeYoung donated the rare 5.03-carat red diamond to the National Museum of Natural History of the Smithsonian Institution in 1987, to be added to the National Gem and Mineral Collection. He also donated a 2.86-carat fancy intense pink diamond that came from the Williamson mine in Tanzania, to the Institution. The two diamonds are exhibited side by side at the Natural History Museum.

What makes a diamond red?

The cause of the extremely rare deep red color of certain diamonds is not understood but might be related to defects in the crystals’ atomic structure. The DeYoung Red Diamond is one of the largest known natural red diamonds. It is a modified round brilliant cut diamond graded by the Gemological Institute of America (GIA) as VS-2 in clarity and natural fancy dark reddish brown in color, weighing 5.03 carats.