Nacreous internal layer of a shell (6-2-5)

I believe the answer is:

mother-of-pearl

(Other definitions for mother-of-pearl that I've seen before include "girl's mum" , "Iridescent material used in ornamentation" , "Internal layer of shell" , "Ornamental material" , "Nacre" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.