Compressing a gas (or reducing its temperature) can form "agglomerations" in the form of liquid drops and solid grains.
But if there's only one particle in the system, can it be assigned with a phase (based on the given temperature and pressure), or is phase meaningless (i.e. arbitrary) in this case? In particular, in colloids of nanoparticles, is there any purpose in specifying the phase of the nanoparticles in the colloid?