is a “black diamond” the same stone as onyx?

i have heard the term “balck diamond” a lot laterly and it is usually refering to a rather expensive jewelry item— however i remember when we use to refer to the Onyx as a black diamond.. what I want to know is are they the same stone? or is a black diamond in fact totaly different?

The black diamonds you see today are in fact “Black Diamonds”…Black Onyx by the way is actually chalcedony that has been dyed black…

Diamond Black Onyx
Diamond Black Onyx
Diamond Black Onyx