MARCO U. MARTINOLICH , SOCIETÀ ANONIMA DI NAVIGAZIONE A VAPORE.
image by Zeljko Heimer, 17 October 2004
The flag is blue with a white diamond throughout. Rosanoski’s 2011 comment identifies a later FOTW page error: the diagonally quartered red-and-white flag belonged to Capponi & Freno, not Martinolich.
The post-war concern continued to use the same flag, as recorded by US Navy 1961 and Stewart 1963.