The mammoth briolettes are amazing! They are huge! Each on would be used as a focal, but equally they would make the most show stopping nacklace all used together.
There are around 13 beads on each strand ranging in size from 18x13mm to 22x15mm approximately.
Natural black onyx like this is not always completely black. Some beads have slight brown sections that have a certain translucence. It is really beautiful, and not in any way a defect.