Black Onyx, also know as black agate, is dyed black chalcedony. Chalcedony is made of tiny crystals of quartz that are not visible to the naked eye. Natural black chalcedony is so rare that all black chalcedony is grey chalcedony that has been treated by chemicals to turn shiny black. Black Onyx is the top-selling chalcedony in the market and was commonly used in Art Deco jewelry as well. Clean with warm, soapy water. Use of ultrasonic and steam cleaner is usually safe.

• Treatment: Dyed
• Uniform opaque black
• Dyed black chalcedony