The Udachnaya pipe (Russian: Уда́чная, IPA: [ʊˈdat͡ɕnəɪ̯ə]; lit.

'Lucky') is a diamond deposit in the Daldyn-Alakit kimberlite field in Sakha Republic, Russia.

[1] It is an open-pit mine,[2] and is located just outside the Arctic Circle at 66°26′N 112°19′E / 66.433°N 112.317°E / 66.433; 112.317.

[3] Udachnaya was discovered on 15 June 1955, just two days after the discovery of the diamond pipe Mir by Soviet geologist Vladimir Shchukin and his team.

As of 2010[update], Udachnaya pipe is controlled by Russian diamond company Alrosa, which planned to halt open-pit mining in favor of underground mining in 2010.