  We establish and develop a correspondence between certain crystal bases
(Kashiwara crystals) and the Coulomb branch of three-dimensional $ \mathcal{N}
=4 $ gauge theories. The result holds for simply-laced, non-simply laced and
affine quivers. Two equivalent derivations are given in the non-simply laced
case, either by application of the axiomatic rules or by folding a simply-laced
quiver. We also study the effect of turning on real masses and the ensuing
simplification of the crystal. We present a multitude of explicit examples of
the equivalence. Finally, we put forward a correspondence between infinite
crystals and Hilbert spaces of theories with isolated vacua.
