The United States Air Force is unique in that its three Senior Noncommissioned Officer (SNCO) pay grades, E-7 to E-9, are bifurcated into two distinct types of positions, with one of them—called First Sergeant regardless of the grade—serving as an enlisted advisor to Air Force Commanders at various organizational levels. First Sergeants are designated by the addition of a diamond, known as “lozenges” in heraldry, to the insignia associated with their grade; an E-8 First Sergeant, for instance, would wear a Senior Master Sergeant with diamond insignia.
First Sergeants had been around long before the United States Air Force was created in 1947, and in fact diamonds had been used as early as 1847 for their insignia. But it was the Air Force that transformed First Sergeant into a job or position rather than solely as a rank, with only Master Sergeants (E-7) eligible for the position until the establishment of the E-8 and E-9 pay grades in 1958. The Air Force brought back the diamond for First Sergeants in 1954, largely at the urging of two MAJCOMs: Strategic Air Command and Tactical Air Command.
The E-8 First Sergeant metal rank insignia is worn primarily on sweaters (Blue Pullover, Blue or White Cardigan) and coats (Topcaot and All-Weather Coat) rather on traditional dress uniforms. Its wear on the Lightweight Blue Jacket was phased out in 2010 after three dozen years of authorization.
More E-8 First Sergeant Insignia and Devices