Hi Judy
Thanks for showing. your beads also show the typical wood type of circles that black coral has. I just attached a Picture of a rough black coral branch which shows These circles on the inside of the branch. I think the more deep black, the more solid black coral is. Ive seen black coral beads that are entirely black without any circles or bandings but this is quiet rare I think.

Ive attached another small strand of black coral beads where the seller insisted that it should be at least 100 years old .. but who knows ..

good luck
sandro