How a crystal grows and is shaped  influences its vibration - that which we feel is its energy assistance. So this too is important in how we respond to a crystal and its healing help for us not just its colour, internal structure and mineral content.

Also the shape externally or something "within" the crystal means our eyes as we look at a crystal or group are receiving visual cues that may trigger a happy or sad memory which we can then work with.

The shaping by man also has its influence on whether we feel a crystal helps us or not. For example a crystal shaped as an Angel may help you to feel supported or not.