A Sotheby's employee holds a rare 52.82-carat white diamond ring at Sotheby's auction house on April 12, 2010 in London, England. Price: 7 million USD. (Photo by Dan Kitwood/Getty Images)

A woman takes a selfie in front of a Lunar New Year display featuring sheep at a shopping mall in Hong Kong, February 13, 2015. (Photo by Bobby Yip/Reuters)

A man dressed as Darth Vader goes through the turnstile at Lermontovsky Prospekt station on the Moscow metro in Moscow, Russia on May 4, 2017. (Photo by Vyacheslav Prokofyev/TASS)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on August 16, 2016. (Photo by Mudra László/Rockstar Photographers)

Members of the Times Square Alliance snow clearing team take a photo on a snowbank at Times Square in the Manhattan borough of New York January 23, 2016. A winter storm dumped nearly 2 feet (58 cm) of snow on the suburbs of Washington, D.C., on Saturday before moving on to Philadelphia and New York, paralyzing road, rail and airline travel along the U.S. East Coast. (Photo by Shannon Stapleton/Reuters)

Visitors dressed in superhero costumes attend the Paris Comics Expo at the Parc Floral in Paris, France, April 15, 2016. (Photo by Charles Platiau/Reuters)

Michelle Rodriguez attends the De Grisogono Party during the 71st annual Cannes Film Festival at on May 15, 2018 in Antibes, France. (Photo by INSTARimages.com)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)