For formal occasions the Jacks adopt a color scheme of greens and blues (or dark green and gold for non-graduates of Blackjack).
Per Mercenaries Supplemental 2, page 53.
Templar, Mercenaries Supplemental 2 (color plates)
The Jacks' insignia is similar to that of the Blackjack School of Combat, using a jack of spades playing card as its base, but instead of wielding a clud, this one-eyed jack bears a hatchet similar to the one used by a Hatchetman BattleMech. Per FM: Mercenaries Supplemental II, page 53.