I have seen pictures of both Ella ( GD Serge) and Militza ( GD Peter) wearing crescents, but unfortuntely have no copies. Also Arch Duchess Marie Josepha (daughter of the King of Saxony & mother of the last Austrian Emperor). They were mainly to be worn on less grand occassions than required a tiara as remembered by Consuelo Vanderbilt Balsan in her memoirs" The Glitter and the Gold". In popularity they seem to have come second only to stars.My mother owns a pretty sapphire and diamond example and one can see the original fittings where it could be adapted for wearing in the hair or as a pendant. The victorian workmanship is excellent...far superior to most of today's craftsmen
The picture of the Archduchess has recently been posted on the Marie Josefa page of the Hohenzollern section.