Gemstone weapons are a special type of weapon introduced in the Borderlands 2 DLC Tiny Tina's Assault on Dragon Keep. They appear as standard purple rarity weapons with a special material and prefix, and have slightly modified stats compared to standard weapons. Both the prefix and skin correspond to a specific type of mineral, gem, or stone, thus giving rise to the "gemstone" designation.
Unlike other special weapon types, Gemstone weapons have no part, element, or accessory limitations other than the material. However, there is no available Gemstone material for Rocket Launchers, thus excluding Gemstone weapons from that type. Additionally, a bug in the Gemstone loot tables prevents Gemstone Maliwan Sniper Rifles from being produced, generating a Gemstone Maliwan SMG instead.
There are 8 prefix and corresponding material variations for Gemstone weapons, one for each brand. Regardless of parts, accessories, or elemental type, any weapon with a Gemstone skin will use the brand-specific prefix.
- Bandit - Quartz
- Dahl - Emerald
- Hyperion - Diamond
- Jakobs - Citrine
- Maliwan - Aquamarine
- Tediore - Cubic Zirconia
- Torgue - Rock
- Vladof - Garnet
In addition to the obvious visual and name changes, Gemstone weapons have combat-relevant differences when compared to standard purple rarity weapons.
The only well-understood difference that Gemstone weapons possess is an extra bonus to critical hit damage. This bonus is relatively small, ranging from 6.5% to 7.5% depending on brand and weapon type, and stacks with any existing critical hit bonuses. The specific bonuses are:
- Jakobs Assault Rifles: +6.5%
- Jakobs Shotguns: +6.5%
- Pistols, all brands: +7.5% multiplicative
- All other weapons: +7.5%
For pistols, the critical hit bonus is not added to the current total critical hit bonuses. Instead, the bonus is multiplicative, effectively multiplying the total damage dealt on critical hit by 1.075. This makes all skills, Badass Rank bonuses, or other critical hit modifiers 7.5% more effective when using Gemstone pistols.
Gemstone weapons also display a variety of additional effects which are less understood, as they are harder to verify mathematically. Displayed effects include bonuses to recoil reduction and accuracy, though indications are that these bonuses are actually to less obvious mechanics such as accuracy recovery.
Not all weapons will show these modified stats on the weapon card. Generally, the bonuses granted by the Gemstone material will only be displayed for weapons which already modify that particular statistic, such as weapons with a critical hit accessory or most Jakobs brand weapons.
Gemstone weapons are obtained from one source: Butt Stallion. Once she returns to Flamerock Refuge after the completion of A Game of Games the player will be given the opportunity to feed her 5 Eridium. Once fed, Butt Stallion will produce a random weapon of anywhere from green to legendary rarity, with higher rarities being less common. If the weapon is of purple rarity it has a high, but not guaranteed, chance to be a Gemstone weapon.
Since there is no limit to the amount of times Butt Stallion can be fed Eridium, the availability of Gemstone weapons is theoretically infinite. However, the chance of a Gemstone weapon appearing is very low, near or possibly below 10%, making the practical supply of Gemstone weapons limited.
- Gemstone weapons are the only weapons in Borderlands 2 which inherit special statistics or other bonuses from the weapon's material.
- As mentioned above, a bug in the Gemstone loot tables prevents Gemstone Maliwan Sniper Rifles from being produced. Whenever a Gemstone Maliwan Sniper should be generated, a Gemstone Maliwan SMG will be produced instead. This SMG will have the same name, prefix, and statistics as a standard Gemstone Maliwan SMG, but will use the Sniper Rifle material rather than the correct SMG material, which maps poorly to the SMG shape.
- As with standard purple rarity weapons, Gemstone Hyperion Pistols may spawn with either the Dart or Spiker barrel, which automatically elevates their rarity to E-tech. This same bug also makes it possible to obtain a non-elemental Hyperion Dart or Spiker with a Gemstone skin.