Get to Know the Hope Diamond’s Keeper

We caught up with Dr. Jeffrey Post to hear the story of this infamous blue diamond, see what makes the National Gem and Mineral Collection so special and learn about the countless things minerology can reveal about the past and future.

The Hope Diamond came to the Smithsonian’s National Museum of Natural History in 1958. Since then, museum scientists have uncovered a lot about the diamond’s intriguing past. (Dane A. Penland, Smithsonian)
The Hope Diamond came to the Smithsonian’s National Museum of Natural History in 1958. Since then, museum scientists have uncovered a lot about the diamond’s intriguing past. (Dane A. Penland, Smithsonian)

The Hope Diamond has a complicated past. It came from India and was sold to King Louis XIV in 1669 as part of the French Crown Jewels. During the French Revolution, the diamond was stolen, resurfacing in London in the early 1800s when it was bought by Henry Philip Hope. From then on, the gemstone passed from person to person until it was donated to the Smithsonian’s National Museum of Natural History on November 10, 1958.

Today the diamond lays in the museum’s Hall of Geology, Gems, and Minerals, under the care of Dr. Jeffrey Post, the Curator-in-Charge of Gems and Minerals.

We caught up with Post to hear the story of this infamous blue diamond, see what makes the National Gem and Mineral Collection so special and learn about the countless things mineralogy can reveal about the past and future.

It's been 62 years since the museum acquired the Hope Diamond. What have we learned about the diamond since then?

Most of our visitors see the Hope Diamond as a valuable gemstone with a long human history. But it's not only a historic jewel. It’s also a very interesting scientific object. Since 1958, we’ve added science to the story about the Hope Diamond.

Two gems glowing red in the dark.
Many blue diamonds glow orange under ultraviolet light, but with different shades and strengths. The Hope Diamond is the larger diamond in this image. Chip Clark, Smithsonian

When the diamond first came to the museum, no one knew that after exposure to ultraviolet light it would phosphoresce a bright orange color, like an ember at the bottom of a barbeque grill. That was only discovered in the late ‘60s. And now with even better instruments, we know the diamond is actually emitting both red and blue-green light. It just looks orange to our eyes. We've also realized that all blue diamonds phosphoresce, although they each emit a slightly different color. That phenomenon is caused by a boron impurity that also gives the diamonds their blue color in ordinary light.

Another thing we’ve been able to do with modern science is recreate the cutting history of the Hope Diamond. Through computer simulations, we modeled how the Hope Diamond was cut from the French Blue owned by King Louis XIV and that came from a diamond from India. This research led us to two strong conclusions: First, the Hope Diamond is the recut version of the French Blue diamond. Second, by looking at how it would have been recut, we determined that everything that was removed had to have been ground away. So, there are no other pieces of the Hope Diamond in the world.

What excites you most about your work besides getting to care for the Hope Diamond?

We work in this incredibly interesting place where objects, history and people converge. Every day, I learn something new. I get to learn about and have held in my hand some of the Earth’s great treasures.

I also love going into the Hall of Geology, Gems, and Minerals and watching people interact with the objects on display. I really do believe that gems and minerals can act as unintimidating portals into science. I love watching people experience the thrill of discovery when they realize these things came out of the Earth. The knowledge that these minerals and gems form naturally in such beautiful, geometric shapes is something that gives people a sense of awe.

What are some of your favorite minerals or gems in the collection?

Whichever one is in my hand at the time! But really, it is hard to pick one. Every day I walk into our vault area and my eye is caught by something I haven’t looked at in a long time and that becomes my favorite mineral for the day.

A pale yellow diamond on a teal background.
Like the Hope Diamond, the Oppenheimer Diamond gets its color from an impurity. Nitrogen makes the uncut gem a pale yellow. Chip Clark, Smithsonian

If there was a threat to the collection and I had to grab whatever I could to take, one of the things I would grab is a diamond crystal called the Oppenheimer Diamond. There are very few large diamond crystals preserved in the world. It’s just this beautiful shape and pale yellow. It is truly a treasure. You could travel the world’s many museums and not find another one. We have many unique objects, but that is one I’ve always found particularly special.

What are some surprising things that objects in the collection have revealed?

We have another blue diamond called the Blue Heart Diamond. While the Hope Diamond phosphoresces bright orange, the Blue Heard Diamond emits a whitish blue color. Looking at the phosphorescent difference between those two diamonds prompted us to look at a bunch of other blue diamonds. We realized phosphorescent spectra could be used as a fingerprint for any specific blue diamond. That was a surprising revelation, and we couldn’t have done that research without the Blue Heart Diamond.

A blue, heart shaped diamond on a dark background.
The Blue Heart Diamond is the second blue diamond in the Smithsonian’s collections. It also glows after exposure to ultraviolet light. Chip Clark, Smithsonian

What does mineralogy tell us about the world’s past, present and future?

Minerals are the basic building blocks of solid Earth and the solid solar system. Everything we know about the history of a meteorite, a moon rock or an Earth rock is because of information stored in its minerals. Even fossils are preserved in minerals. So, for example, if I can understand how minerals have been altered because of changes in the environment over the course of time, perhaps I can predict what will happen in the future.

One way we do that is by making polished sections of mineral crystals to look at their interiors — much like looking at the cross-section of a tree and using its rings to trace its history. These sections show us what’s changed in a mineral from when it was created to present day. It’s like a time capsule that has the information about when and where that mineral formed.

The value of the collection is that we can keep interrogating those minerals. None of us are arrogant enough to think we’ve learned everything we can about the collection. When I think of my early career and what questions our field was asking and what technology we had... I never could have even predicted the kinds of questions we can ask and answer now. We maintain this collection so that it’s continuously available. Scientists will always have access to it.

Meet a SI-entist: The Smithsonian is so much more than its world-renowned exhibits and artifacts. It is a hub of scientific exploration for hundreds of researchers from around the world. Once a month, we’ll introduce you to a Smithsonian Institution scientist (or SI-entist) and the fascinating work they do behind the scenes at the National Museum of Natural History.

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