On a shield-shaped, embroidered device with a semi-circular base 3 1/4 inches (8.26 cm) in height and 2 3/8 inches (6.03 cm) in width overall, blazoned: "A shield parted per pale wavy Purpure and Argent, a pale wavy Sable, the sinister bearing a demi-corpse of a conquistador seen from the back, highlighted of the second, shaded of the third, wearing a Morion helmet and carrying over his sinister shoulder a sword point to sinister, both Grebe (Steel Gray) detailed and shaded as the armour", all within a 1/8 inch (.32 cm) Black border. Attached above the shield a Purple tab inscribed "SANTIAGO" in White letters and edged with a 1/8 inch (.32 cm) Black border.
Purple and white are the school colors. The Morion helmet is the traditional armour worn by the Spanish settlers of California. The "S" shape symbolizes the name of the school ? Santiago High School.
The shoulder sleeve insignia was authorized 24 May 2004.