Onyx cufflinks have always been the mainstay in men's formal fashion. We often call black stones onyx, but what are they really? Onyx is considered a type of chalcedony stone. It crystallizes in order to form the black onyx stone that is polished and sold in jewelry, accessories, and on buttons. If you enjoy a beautiful dark stone, then you might consider black onyx as the perfect choice. Onyx can be made to shine or be slightly dull depending on choice. It can also be part of silver plating like the Sterling Silver plated Onyx formal set. This perfect wedding set is a rounded cufflink with silver stud, and a plate of onyx rather than a fully rounded stone. Another choice is the domed onyx which does offer a little more in the silver plating, and it is still a formal look. Onyx can be made into a variety of shapes like rectangular bars or oval shapes with a double black covering on the cufflink. You also have the choice of going with a mosaic of semi-precious striped onyx that is not only black onyx but other forms of chalcedony.