Rainbow fluorite is a type of multi-color fluorite that combines the properties of the various colors of fluorite in one. Normally, rainbow fluorite exists in massive form, and thus, the ones you see in crystal shops are always cut and polished ones. The colors in rainbow fluorite can range from blue, green, light grey, violet, yellow, black, and colorless.
In addition to the general properties for fluorite, rainbow fluorite has additional metaphysical characteristics brought about by the various colors. The colorless portion has crown chakra stimulating properties, and it’s believed that it can assist with aligning all the chakras below it and facilitate energy transmission from the ethers to one’s being.

A piece of rough uncut rainbow fluorite. Green is the color shade most often seen in all forms of fluorite.

My rainbow fluorite, which has been cut into the shape of an obelisk (signifying male energy).
Green is a common color in rainbow fluorite and accentuates the “minty freshness” attribute that humans have come to associate with the fluorite mineral. The green color brings a healing, soothing quality to fluorite, and cleanses away negativity from one’s environment and being. It’s also used for soothing and relieving disorders associated with the digestive tract.
Violet is often seen in rainbow fluorite, as streaks or bands of color. It is the color of spirituality, and is associated with psychic and spiritual growth; the realm of the Third Eye. In this case, the violet in fluorite is believed to confer rationality to one’s intuitive qualities, and helping one to communicate that to others more accurately. Violet fluorite has been used for disorders related to organic “structures”, such as the bones, and cells.

You can observe violet bands as well interspersed with the green.
Blue is another color sometimes seen in rainbow fluorite. The blue promotes more orderly and rational thinking, as well as communication. As blue is the traditional color of calmness and serenity, people feeling stressed and harried could benefit from having some blue fluorite around. Blue fluorite has been used for helping with eye, ear, nose, and throat problems.
Yellow is also sometimes encountered in rainbow fluorite specimens. The yellow color promotes creativity and analytical endeavors. Yellow fluorite enhances group cooperation, and would be useful on an office desk. It has been used in helping with liver problems and toxin removal from the body.