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)

Anglers cast lines through holes into a frozen river during an ice fishing competition at the Hwacheon Sancheoneo Ice Festival on January 7, 2012 in Hwacheon-gun, South Korea. (Photo by Chung Sung-Jun/Getty Images)

A woman holds a placard that reads, “I am Charlie”, during a vigil to pay tribute to the victims of a shooting by gunmen at the offices of weekly satirical magazine Charlie Hebdo in Paris, at Trafalgar Square in London January 7, 2015. (Photo by Stefan Wermuth/Reuters)

A reveller parades on stage at the annual Trinidad and Tobago Red Cross Society's Children's Carnival Competition at the Queen's Park Savannah in Port-Of-Spain February 7, 2015. (Photo by Andrea De Silva/Reuters)

Russian Police academy female cadets march during a rehearsal for the Victory Day military parade at Dvortsovaya (Palace) Square in St Petersburg, Russia, Wednesday, May 7, 2014. Victory Day, marking the defeat of Nazi Germany, is Russia's most important secular holiday celebrated on May 9. (Photo by Dmitry Lovetsky/AP Photo)

An Amur tiger walks across a passageway after a news conference at the Philadelphia Zoo, Wednesday, May 7, 2014, in Philadelphia. The see-through mesh pathway called Big Cat Crossing is part of a national trend called animal rotation that zoos use to enrich the experience of both creatures and guests. (Photo by Matt Slocum/AP Photo)

A helicopter of the Food and Agriculture Organization of the United Nations (FAO) flies through millions of Locusts as spreads pesticide to fight against a swarm of locusts threatening to reach Amparihibe village on May 7, 2014 in Tsiroanomandidy, Madagascar. FAO mission is to fight the locust's swarm with an insecticide. (Photo by AFP Photo/RIJASOLO)