These are gorgeous pieces of Blue/Black Kyanite.
In general, kyanite can help align and open all of the chakras. Kyanite can also aligns all layers of the aura.
Blue Kyanite is especially good for working with the Throat Chakra and communication issues. Blue Kyanite helps to speak one’s truth with clarity, making it a great stone for public speakers and performers. Blue Kyanite is also useful for healing throat and voice ailments. Blue Kyanite also facilitates an alignment of all the subtle bodies, creating a larger and stronger aura.
Blue Kyanite is also an excellent Third-Eye Chakra stone, that can pull very high vibrations in through this chakra to be processed as messages from other realms.
Blue Kyanite can also be used to promote lucid dreaming and astral travel.
Black Kyanite is very grounding, magical and protective. They call it a Wizard’s stone