On rare occasions they can be found by opening Crimson Lance Chests, and even less commonly by the occupants of Lancers.
In the first Borderlands game, Pearlescent items are included in The Secret Armory of General Knoxx DLC, where they can be dropped by Crawmerax the Invincible, Badass Bruisers, Lance Pyros, Badass Engineers, and Drifters.
