Pearlescent

Pearlescent (Sometimes referred to as Cyan) weapons/items are a confirmed rarity type encountered exclusively in the third DLC, The Secret Armory of General Knoxx. They can be dropped by Crawmerax the Invincible, Badass Bruisers, Lance Pyros, Badass Engineers, Drifters, on rare occasions can be found by opening Crimson Lance chests, and even less commonly by the occupants of  Lancers.

Items with pearlescent rarity
These are the only confirmed pearlescent items, all added with DLC3. Each manufacturer has only 1 pearlescent weapon, and each weapon type has only 1 pearlescent(with two exceptions, there are no pearlescent Assault Shotguns or Semi-Automatic Sniper Rifles). There are 3 pearlescent shields, one of which is an Atlas.

Before General Knoxx

 * Pearlescent was an old bug in Borderlands before the advent of the Secret Armory of General Knoxx where "white" weapons would appear over "orange" weapons in the inventory. It was fixed in the patch preceding DLC3. For all information for this old bug, visit Pearlescent (Before General Knoxx).