This is something I have noticed since my teens, but not written down before. It is the sense of a transition between a slightly disorganized field and a crystallizing field.
It is especially tangible in sitting mediation, where the transition usually happens within the first few minutes, and it is also tangible in daily life, where the sense of crystallization is more or less present depending on how much sitting practice I do and other things going on. (During the couple of months last fall where any sense of I fell away, the emptiness itself took on a crystal quality.)
It shows up as a tangible sense of crystallization (or not), and also visually in the energy fields of myself and others. When there is no or less crystallization, there is also less awareness of the energy field and what it represents. As it is brought more into awareness, the crystallization also takes place.
So again, it appears to be more literal than it may be taken by many. There seems to be a literal reconfiguring of the subtle energies which is experienced, and seen, as a crystallization.