A gold color metal and enamel device 1 1/4 inches (3.18cm) in height overall consisting of gold sun rays behind a scarlet disc surmounted by a blue (light blue) saltire bearing two gold arrows saltirewise with points upward, and charged at the top and in base with a gold sea lion, all above a gold scroll inscribed in black letters "FAST COMPETENT ACCURATE."
The two sea lions symbolize the unit's two campaigns, New Guinea, Southern Philippines, World War II. The blue saltire on the scarlet field was suggested by the State Flag of Mississippi. The arrows represent the fire power of the organization. The sun rays allude to the awarded Philippine Presidential Unit Citation. Scarlet and yellow (gold) are colors used by Artillery units. The first letter of each word in the motto (Fast Competent Accurate) and its corresponding number within the alphabet denote 631, the organization's numerical designation.
The distinctive unit insignia was originally approved for the 631st Artillery Group on 8 July 1970. It was redesignated for the 631st Field Artillery Group on 15 June 1972. On 13 March 1979, the insignia was redesignated for the 631st Field Artillery Brigade.