When you dream about an ice crystal, the reflection of a situation and / or how you feel represents the connection with your heart, your emotions, feelings and so on. The ice crystal is your frozen part of the situation and / or the frozen part that is preparing for a new situation.
Another explanation is the experience of stillness, winter, death and rebirth. Another explanation is the winter season that is emphatically present in your life and / or the situation you are in.
Another explanation is that the ice crystal reflect your emotions, feelings, tears; expressing that which no longer suits you. Letting go, processing and becoming aware of that. Another explanation is that your heart and your feelings have no flow of ideas and thoughts and / or experience stagnation at the moment.
You should try to express and unwind so that you can let in warmth and change your thoughts. You may also feel uncomfortable about yourself. You may even react a bit cold.