Black lace agate is another name for black sardonyx. Sardonyx 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.