Classed as a gem, onyx is composed of earthy-toned or black and white banded agate. In recent years, banded chalcedony of any color has also been referred to as onyx. Onyx’ appeal lies in its translucency and is excellent at highlighting spaces and creating distinctive colorful features. Many designers choose to backlight onyx to showcase its translucency and unique bands and patterns. While not as hard as marble, granite or quartzite, onyx is chemical resistant and can be sealed and treated for low volume areas carrying water. Pricier than most other stones, onyx works well to create opulent effects with other stones and material through accents and singular architectural features.