Mila Kunis for ethical emerald company Gemfields

As the company's new brand ambassador, the Hollywood actress has added her face to Gemfields's latest advertising campaign, photographed by Italian fashion legend Mario Sorrenti and styled by Anastasia Barbieri.

The "Oz: The Great and Powerful" star's latest role as a young Theodora (later to become the Wicked Witch of the West) sees her character heading to the emerald city.

Life has once again copied art in the new campaign which features Kunis wearing one-of-a-kind emerald and ruby pieces created by Gemfields' designer partners including Alexandra Mor, Amrapali, and up-and-coming Londoner Dominic Jones. Also featured is famous Russian luxury brand Fabergé, which was acquired by Gemfields earlier this year.

Kunis recently toured Gemfields' Zambian mine, Kagem, which produces approximately 20 percent of the world's emeralds. "Mila has blown me away with her energy, enthusiasm and dedication," said Gemfields CEO Ian Harebottle. The actress was taken on tours of the company's environmentally-friendly mining practices and visited a number of Gemfields-sponsored community projects, among them schools and a farming cooperative.

"I truly believe in Gemfields' mission of ethical mining, and I absolutely have fallen in love with the rarity, beauty and history of emeralds," added Kunis.

London-based Gemfields is the world's leading colored gemstone producer, but this is the first time the company has hired a brand ambassador. The adverts are set to run around the world in publications including Vogue, Vanity Fair, Bazaar and W.

Gemfields is also revamping its website and will release a large-format print book on emeralds. The brand will unveil a collaboration with 37 international designers for an exclusive collection of colored gemstone jewelry on March 14 in London.

Born in the Ukraine, and raised in California, 29-year-old Mila Kunis is also the face of Dior's Miss Dior handbags.