Jubilee Marking 60 Years on the Throne
Puzzle 17 of Endangered Species Pack
Question is: Jubilee Marking 60 Years on the Throne
and the answer is: DIAMOND
Word Meaning:
DIAMOND — (uncountable) A glimmering glass-like mineral that is an allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron.
Definitions from Wiktionary.