The stones in the pendant (from top to the point) are: Amethyst, Blue Aventruine, Turquoise, Green Aventurine, Yellow Aventurine, Peach Aventurine, Red Jasper.
The seven chakras are the main energy centers of the body. You've probably heard people talk about "unblocking" their chakras, which refers to the idea that when all of our chakras are open, energy can run through them freely, and harmony exists between the physical body, mind, and spirit. Chakra translates to "wheel" in Sanskrit, and you can imagine them like wheels of free-flowing positive energy.