The Order of the Most Holy Annunciation has a continuous history since its foundation by the Count of Savoy in 1362, making it, after the Order of the Garter, the second oldest extant Order of Chivalry.
There is an illustrated account of the Order from Wikipedia at Supreme Order of the Most Holy Annunciation As that account shows the Order has some distinctive features, including having not one but two collars, and which appear to be worn of an evening, and only it started using a riband in the twentieth century.
Crown Prince Umberto wearing the Grande Collana
King Umberto II in later life wearing the Piccola Collana together with the riband of the Order of SS Maurice and Lazarus and the stars of both Orders
I have posted about the Order in 2011 at Order of the Annunziata and in 2012 at Order of the Annunziata 650. This post has a series of links to additional information about the history of the Order.
The collar badge of the Order of the Most Holy Annunciation and dated to 1920-1940
Museum of Orders Tallinn