Borderlands 1 Pearlescent Guide
Finding pearlescents is one of the best feelings in Borderlands 1, they are far and away the rarest class of guns, and have about a 1 in 5000 drop rate. So for every 5000 guns you can loot, you can expect to find just a single pearl. There are individual items and weapons (like the golden eridium mega cannon) that are rarer than the pearls, however this guide should help in finding those as well.
Pearls are ONLY available in the General Knoxx armory DLC, they can not be found elsewhere on Pandora except in the maps added in this DLC. They are nice cyan color weapons, and are placed above even the rarest orange weapons in your inventory.
There are a total of 12 pearls in the game, and they are represented by every weapon type except assault shotguns and semi-auto snipers. Three of the pearls are shields. While there is no clear distinction in the drop rate of the individual items, they can only be obtained from certain enemies in the game. For instance, a badass rocketeer has a 0.02% chance of dropping an undertaker, but a 0% chance of dropping an Aries. This goes for all enemies who have any chance of dropping pearls except for two instances. Crimson lance chests and the raid boss Crawmerax can drop any of the 12 pearls.
To obtain the mission to kill Crawmerax the Invincible, you must complete the entirety of the General Knoxx DLC and go to the T Bone Junction Bounty Board and accept the mission You. Will. Die. You should be level 69 before fighting Crawmerax to ensure you have the best possible loot to fight him and also will receive the best possible loot when you do. I will always recommend Lilith to farm Crawmerax, but it is obviously possible with all characters.
Killing Crawmerax is one of the most well known and effective methods of obtaining pearls. He is a large crab enemy who can only be damaged by hitting one of his 6 critical hit spots. There is a well known glitch to kill Crawmerax where a player gets themselves wedged into a corner of the map where they can't be hit by him or any of his small craw enemies.
You achieve the glitch by running to the left immediately after reaching the top of the elevator in Crawmerax's Lair and run towards the wall. There is a small gap in between the ledge and wall, and if you crouch you can wedge your character into this gap. This works best with Lilith and Mordecai since they have the smallest character models. On the GOTY edition, this may not work with Brick or Roland because the geometry of the ledge has been shifted slightly and their models may be too large. Once you're in the wedge, you can safely shoot Crawmerax from a distance while he can only roar and raise his legs. The only challenge with this method is shooting his back critical spot. If you're using Lilith, jump up from the wedge and immediately enter phasewalk. Move yourself behind Crawmerax and hide behind one of the three pillars in the arena. When you exit phasewalk, Crawmerax will not turn around because without a direct line of sight and ground contact he can not track you. Run out from behind the pillar and jump as you come into view of his back. While you aren't touching the ground, he will not turn around to fight you because he can not track you. While in the air, deal as much damage to his critical spot as possible with your strongest non-elemental weapon. You should be able to kill him in one jump, but keep repeating the process until he's dead.
If you don't wish to use the glitch, your best bet is to have one normal, one corrosive, one lightning, and one fire weapon in each weapon slot. You'll be using the normal weapon against Crawmerax, corrosive against Armored Craw Worms, lightning against craw maggots, and fire against green craw worms. Use a transfusion grenade mod and either a health regen shield or a fast recharge shield to preserve and regain health. The best strategy is to keep distance between Crawmerax and yourself, either using the pillars or your characters abilities to create distance. Even with the strongest shields in the game, you can only take 2 direct hits from Crawmerax, so do your very best to keep him away while also using your elemental weapons to damage and destroy his minions. When you pop a critical hit spot on Crawmerax, he stops and roars, which can be an excellent safeguard in a close situation. I recommend using a masher revolver, skullmasher sniper, anarchy SMG, or a double stinger SMG against Crawmerax. Shotguns can also be useful in certain situations. Your number one goal is to deal as much damage per second to his crit spots, and these weapons will help you accomplish that. A legitimate fight against Crawmerax was designed to be handled by 4 level 69 players who are fully kitted, do not be surprised or discouraged if you lose, especially on your first few attempts.
Once he is dead, he drops the best possible loot in the game, and a lot of it. Sift through what is dropped and pick up what you like. Each solo kill drops around 65 weapons, so you should expect to see one pearl in your first 78 kills, but of course you could have horrible luck and not see one until you've killed him over 100 times or have amazing luck and see one on your first kill. Either way, the long term average will probably be 1 pearl for every 78 kills.
You can leave and re-enter Crawmerax's lair, allowing you to fight him infinite times on the same game load, but eventually the loot on the ground will build up to such an extent that you will not be able to continue fighting him without restarting the game. Once this happens, it's time to loot Crimson Lance chests.
Crimson Lance Chests
Crimson lance chests are also only available in the Generax Knoxx Armory DLC, and do not spawn outside of the maps introduced in that DLC. These are the only chests in the game that can possibly hold pearls, all other chests can not even though they may be in the DLC map.
The number one place to find these chests is the armory itself, so go ahead and complete the campaign and loot the armory normally (with the three minute timer) and allow it to blow up. Then go and talk to marcus in T-Bone junction and after doing a mission where you are asked to kill a certain number of lance troops, you are awarded with re-entry to the armory. Before re-entering, I suggest you get yourself to level 69 to get the best possible loot.
On your way to the armory, while fighting your way through the Crimson Fastness and the horde of lance troops guarding it, there are two randomly placed lance chests along the way. One of them will have a small lance trooper in it and the other will be fully lootable. Enter the armory and kill Knoxx and then make your way to the front doors of the actual armory building where you had to enter the code previously. Now slowly make your way down the hallway, and stop just before you reach the red shield windows. On the other side of the last crate on the right hand side, there is a line on the floor that appears to connect the two different floor areas. Move against the right hand wall while standing on this line and crouch. Slowly move back and forth along with the right side of this line, and you will fall through onto a ledge. Walk off the ledge and you will fall into the second story of the armory without triggering the timer or mission.
There is one inaccessible area of the armory, there is a hexagonal room with pillars inside of it. DO NOT enter this room, as it's the coordinates for the waypoint check to see if you've reached the munitions box. If you enter this room, you will see the first objective of the mission get checked off. Shut off your console immediately or else your game save will get corrupted. All chests are accessible without entering this room, so there's no reason to need to go into it.
As I said, you are on the second layer of the armory, and the chest breakdown is as follows:
1st floor: 1 crimson lance chests
2nd floor: 3 crimson lance chests
3rd floor: 2 crimson lance chests
4th floor: 6 crimson lance chests
loot wall: 12 crimson lance chests
You should be able to loot 24 chests inside the armory, and they are broken down into 15 level 48 and 9 level 60 chests. There are 9 level 48 chests along the loot wall, and all 6 of the 4th floor crimson lance chests are also level 48. All others you find will be level 60. There is no difference in odds of finding pearls in either level chest, but the level of the weapons found may be different.
If you are only after pearls, just loot these 24 chests and see if you get lucky, the other few dozen chests in the armory are irrelevant for pearls. You can exit the armory in two ways, you can either just exit and save the game normally, which will have you respawn at T Bone junction once you restart. You can also just kill yourself using a rocket launcher or grenades which will respawn you at the spawn point before fighting Knoxx.
That's it! Those are the two most effective ways of farming Pearls in BL1. My method is putting them together by killing craw 10 times, and then hitting the armory and exiting once I'm done. I've found that after 10 kills the amount of loot starts to get overwhelming and I get unsure if I'd even be able to pick out a pearl if one dropped. Using this method, I find about 1 pearl per 4 hours of farming or roughly one per day.
If you're interested in farming let me know and we can farm together to make everything easier. If you need a boost to 69 to help with the methods above, I'd be happy to let you tag along during a farming session and you'll get levels from the craw kills. Killing him in a 2 player game is roughly 130k XP so you get at least 1 level per kill except for upper 60s.