White Gems (シロダマ, Shirodama) are items featured in Shadows of the DAMNED. They are the dominant form of currency in the City of the Damned, and are used to purchase drinks, ammunition and Red Gems from Christopher. The gems can also be used to purchase additional alcohol from drinks machines.
Collecting 300 White Gems at any one time will reward the player with the 'Stingy Bastard' achievement/trophy. The best place to accomplish this is in an area with respawning area, such as the swamp in Act 3-2, or the Mikami Head attack sequences in Acts 2-3 and 3-1.