• Sardonyx was the original but unofficial birthstone for August, dating back centuries. When the American Gem Trade Association and Jewelers of America standardized monthly birthstones in 1912, peridot was added as a second August birthstone. Spinel was added as a third August birthstone in 2016 in an effort to modernize and update the birthstone list.
• June and December are the only other months with three birthstones, but various other months have two: the traditional, and the modern.
• Chalcedony [“cal-SAID-any”] is another type of silica, classified as a “microcrystillane form” of silica because the crystals are too small and tightly knit to see without a microscope. Chalcedony is named after an ancient Turkish city called Chalcedon, now a district in Istanbul. The name springs from the Phoenician term meaning “new town.” Chalcedony encompasses an entire family of minerals that have different form and coloration depending on the circumstances of their creation and other minerals present at the time.
• Agate is a translucent variety of chalcedony; jasper is an opaque form. Onyx is chalcedony that’s striped white, grey, and black. Onyx got its name from the Latin word meaning “fingernail” or “claw” because the white bands are the same color as nails. Sard is another type of chalcedony that’s primarily red, orange, or brown because it contains iron oxide. The mineral sard takes its name from an ancient city called Sardis, the capital of the territory of Lydia, located in what is now Turkey. The mineral was common in the area.
• When sard and onyx are mixed together, the result is called sardonyx. The stone is an intriguing mix of colors, with sard responsible for the red-toned hues and onyx contributing white and black streaks.
• Sardonyx is easily carved and has been used throughout history to create bas-relief cameos in stone, commonly depicting the faces of gods, kings, heroes, and beauties. Ladies sported cameos of the face of Venus to bring love; soldiers wore the face of Mars or Hercules into war for courage and protection. Later, artists carved entire three-dimensional scenes depicting battles, coronations, weddings, funerals, and myths. These works of art are called intaglios, from the Italian word meaning “to engrave.”
• Roman rulers used signet rings and seals made of sardonyx in order to imprint wax insignia on important documents because melted wax doesn’t stick to it.
• Sardonyx has historically been a popular gem because it’s always been inexpensive enough so that even the common people could afford a few pieces, unlike more expensive stones like diamonds, rubies, and sapphires.
• One of the most well-known sardonyx cameos depicts the profile of Queen Elizabeth I. According to historical myth, she gave the item to Robert Devereux, the 2nd Earl of Essex, as a gesture of their friendship. The talisman didn’t work very well, as she had him beheaded in 1601. The cameo now resides in the Royal Collection.
• The city of Oberstein, Germany, is world headquarters for cutting and dying minerals in the chalcedony family in order to enhance their colors. Carbon deepens the blacks; iron brightens the reds. Part of this talent with improving these gemstones is due to large local deposits of these minerals, along with a strong local knowledge of the chemistry of dyes. Additionally, in the 1800s, ships traveling back to Germany from Brazil used agate-rich gravels as ballast in their ships, providing a cheap easy source of materials to practice on.
