The Portuguese Diamond - A Giant with a Glamorous Past

Some diamonds sparkle. Others have stories. The Portuguese Diamond does both—and in epic proportions. Weighing in at a jaw-dropping 127.01 carats, this gem is the largest faceted diamond in the Smithsonian Institution’s collection, and it’s just as famous for its glow as it is for its glitzy journey through history.

A Sparkle That Doesn’t Quit

This stone is an octagonal step-cut diamond with an intense internal brilliance and—here’s the cool part—a strong blue fluorescence. Under ultraviolet light, it practically glows, giving it an ethereal, almost supernatural presence. You know those diamonds that seem to light up the room before anyone notices the person wearing them? That’s the Portuguese Diamond in a nutshell.

Its step cut gives it a sleek, geometric vibe, and while it might not throw off the kind of fire you'd see in a brilliant-cut gem, it’s all about the depth and drama with this one. It’s elegant, bold, and a little mysterious.

From Pearls to Platinum to the Smithsonian

Let’s rewind to the 1920s, when the Portuguese Diamond came into the spotlight thanks to none other than Peggy Hopkins Joyce. Actress, socialite, and professional head-turner, Peggy was known for her high-profile romances and her taste for extravagant jewels.

She reportedly acquired the diamond in a trade that included $350,000 worth of pearls—which, back then, was serious money. She then had the stone set into a platinum choker, because why wouldn’t you wear a 127-carat diamond around your neck like a casual accessory?

Later on, the diamond changed hands again and eventually landed in the Smithsonian, where it remains a highlight of their gem collection. If you're ever in Washington, D.C., it’s absolutely worth seeing in person. Photos don’t do that fluorescence justice.

But Why “Portuguese”?

Despite the name, there’s no confirmed connection between the diamond and Portugal. Some legends suggest it once belonged to Portuguese royalty, but there’s no solid historical trail to prove it. Still, the name stuck—and honestly, it sounds regal enough to match the diamond’s vibe.