A Silver color metal and enamel device 1 1/8 inches (2.86 cm) in height overall consisting of a shield shaped blazoned: Per fess Gules and Azure, as a fess a stylized volcanic tuff cone of the second surmounted by the Blessed Mother Mary and Child in base metal and detailed of the second in between in dexter chief the Alpha Omega symbol and in sinister chief a Marianist symbol, all Silver. Attached below the shield, a Silver scroll inscribed "MEMOR ET FIDELIS" in Blue letters. Between the shield and scroll base metal, rayed.
The shield alludes to Saint Louis Schools involvement during World War II as a designated hospital, the 147th General Hospital in the Pacific. Diamond Head is a local landmark of Honolulu and is located just blocks from Saint Louis School. The image of Blessed Mother Mary and Child and the Marianist symbol denote the Marianist Order of the school. The Alpha Omega is symbolic of the schools teachings of God. The inscription "MEMOR ET FIDELIS" translates to "Mindful and Faithful" and is the school's motto.
The shoulder loop insignia was authorized 28 February 2011.