Sardonyx is a type of agate. It is believed to dispel negative thoughts, ease melancholy, increase perseverance, and hone the mind. It is said to increase courage, foster honesty, and bolster self-discipline. Sardonyx is a protective stone, believed to bring good fortune, promote friendship, increase energy, and encourage creativity. This is a stone of courage and strength that is said to aid us when we have an idea we need to convey, whether it is a presentation to a group of people, a confrontation we must get through peacefully, or a matter of love and romance. Sardonyx is one of the birthstones for the month of August, and it is associated with the Zodiac sign of Leo.