Exploring Peridot: The August Birthstone and Its Stunning Alternative Gems August buddies! Let us introduce you to Sardonyx, a variety of silicon dioxide(chalcedony), a stunning alternative August birthstone. It is a brownish-red to yellowish-red gemstone comprehended for conveying its wearers strength and protection. This gemstone is a mixture of a type of orange carnelian called Sard and Onyx. Sardonyx is derived from the Greek terms Sardios and Onyx, which means 'the stone from Sardios (a place in Persia)' and nail or veined jewel, respectively. It is a courageous gemstone that allows the wearer to live life to the fullest and protects them from negative influences.