The deep blue Hope Diamond, arguably the most famous and mystifying diamond in the world, was once specially cut in the 1600s to appear as if a dazzling golden sunburst was emerging from its center.
It was a fitting tribute to King Louis XIV of France, who reigned for 72 years and was known as the “Sun King.” The monarch apparently ordered the diamond to be recut with a series of special facets on the back that produced a translucent area. When the diamond was set against a yellow gold background, the vibrant color shone through, giving the appearance of a sunburst.
A recently rediscovered 17th century lead replica of the Hope Diamond (then known as the “French Blue”) helped unravel the mystery for François Farges, a professor of mineralogy at the National d'Histoire Naturelle in Paris, and Jeffrey Post, the Smithsonian museum's curator of minerals. The mineral scientists used computer modeling of the lead replica to simulate what the actual jewel looked like during the reign of Louis XIV, according to Smithsonian.com.
The Hope Diamond, left, placed next to the lead cast of the French Blue.
Technically, the French Blue was cut with shallow angles and an entirely flat culet on its back, according to Smithsonian.com. Compared to the rest of the stone, the material right in front of the culet at the gem's center would have appeared relatively clear and colorless, like a glass window.
A 1691 inventory of the French Crown Jewels confirmed that the French Blue had been set into gold and mounted on a stick. The mineral scientists believe that if the gem were placed in front of a gold sheet, golden sunrays would have appeared at its center.
Fargas rediscovered the lead replica of the French Blue in 2009 in France’s National d'Histoire Naturelle mineral collections. This was the first time contemporary gem experts could get their hands on the exact measurements of the actual French Blue.
"They didn't even know they had it,” Post told Smithsonian.com. “It was in their collection, but filed under lead specimens."
The French Blue was stolen during the French Revolution in 1792 and went missing for 20 years. It finally reappeared in Britain in 1812 in its present shape and weight.
After being acquired in the 1830s by a rich London banker named Thomas Hope, the 45.52-carat blue diamond would become known as the Hope Diamond. Mined in India and brought to France in 1668, the gem currently resides at the Smithsonian National History Museum in Washington, D.C., where it continues to be a top attraction.