Borderlands 3 Diamond Keys are a new way to unlock powerful loot, all while agonizing over which powerful loot you want the most before the clock runs out.
Gearbox revealed Diamond Keys in a new update on Borderlands 3's upcoming Director's Cut, which is set to arrive on April 8. They work sort of like the Golden Keys you can earn by staying tuned to the Borderlands social media accounts, but they're even more lucrative. Rather than keeping your head on a swivel for Insta posts, you can earn Diamond Keys as a reward for leveling up the new Vault Cards coming in the Director's Cut content - Gearbox says Diamond Keys will be very rare, but it sounds like they'll be worth the wait.
Once you get your hands on a Diamond Key, you'll be able to use it at the new Diamond Armory located beneath the Bridge on Sanctuary III. Activate the Diamond Chest with the key, and shutters on the three surrounding walls will open to reveal a buffet of gear. The trick is, you can only pick one item off of each wall - that's one shield, one weapon, and one grenade - and you only have a limited amount of time to make your choice before the shutters will slam shut again. If you're too wracked by indecision to make all your picks in time, you'll receive a random item from the walls you didn't pick.
Then you get one last reward as the Diamond Chest itself finally opens, revealing a Legendary piece of gear. To sum that all up, one Diamond Key gets you four pieces of gear, including at least one Legendary.
The new Vault Cards will also unlock new cosmetic gear, and even once you clear all their unique rewards, you can keep leveling them up indefinitely for more Eridium and Diamond Keys (as well as higher-leveled versions of the stuff you already got).