Protocol III to the Geneva Conventions
Protocol III (also Additional Protocol III or AP III) is a 2005 amendment protocol to the Geneva Conventions relating to the Adoption of an Additional Distinctive Emblem. Under the protocol, the protective sign of the Red Crystal may be displayed by medical and religious personnel at times of war, instead of the traditional Red Cross or Red Crescent symbols.
Source: Wikipedia — Protocol III to the Geneva Conventions (CC BY-SA 4.0)