This stone can come in a four colors (that I'm aware of).
Blue is what I find most, but have also had green, red and black.
It is said...
-to stimulate the intellect and to help realize that our strengths occur through both love and spirit, helping to dissolve aloofness and negativity
-using it with others can bring results with greater ease
-to be a stone healings, balancing energy, of service, storing information, communicating and teaching
-to help one recognize and experience information used by oneself or in a group
-to help with manifesting by helping to apply insight and focus between mind and matter and with expanding the knowledge base
-to help coordinate balance and integrate the emotional with the intellectual, physical and etheric bodies
-to also be good for those who suffer over/underactive, blocked, or congested chakras.
-to be a helper of the spiritual with discipline, deeper states of meditation, reflection, balancing and raising energies, insight, inner clarity, peace with ones higher self
-to be used to help stimulate development with clairvoyance, clairaudience, clairsentience and telepathy as well as provide access to information on past lives.
-to be a good for creativity by helping clear mental confusion and awakens the finer, inner self by brining knowledge.
-that wearing/carrying apatite can help suppress or increase hunger as needed (good for both needed gain or loss)
-and using at a physical level can help focus healing on the glands, meridians, and organs.
References come from the books:
Love is in the Earth, Melody
Crystal Bible 1, Judy Hall