Upgrade stones

From Outwar Wiki

Upgrade stones are upgrades to your crew that are dropped by raid spawns in Diamond City that help lowered leveled crews obtain upgrades without buying the upgrade itself.

There are a few different types of crew stones shown here. The color of the stone depends on how many upgrades it gives.

Purple Stone		These stones have only one type of upgrade on them
Pink Stone		These stones have two upgrade types on them
Yellow Stone		These stones have three upgrade types on them
Green Stone		These stones have four upgrade types on them
Blue Stone		These stone have five upgrade types on them

Note that it is rare that a raid mob drops upgrade stones, and if it does, it won't drop more elite crew stones unless the mob is a high level. You're more likely to get a Blue Crew Stone from Sigil, Lich of Woe, rather than the Leet Commander.