Hard black lignite used in jewellery (3)
I believe the answer is:
jet
(Other definitions for jet that I've seen before include "Aeroplane" , "A spring in ballet" , "Aircraft engine" , "Jumbo plane?" , "Very black or fast plane" .)
I believe the answer is:
jet
(Other definitions for jet that I've seen before include "Aeroplane" , "A spring in ballet" , "Aircraft engine" , "Jumbo plane?" , "Very black or fast plane" .)