Onyx is a variety of chalcedony zoned, where the layers are clearly distinct. True onyx has siliceous nature.
Onyx Marbles much more common and in varied colors are alabasters limestone made up of calcium carbonate.
These stones are considered high-quality ones, used for coatings and decorative luxury ornamental elements
They can be white opal or colored yellow, green, red, light or dark brown and sometimes blood-red colored.
Material of great beauty is used for both internal and external great value decoration. Their inner quality of being backlighting means they are known as the most precious stones used in interior design.
Here is a photo gallery of onyx we deal.