Often the Center of an Engagement Ring
Puzzle 5 of Shiny Things Piece of Cake Pack
Question is: Often the Center of an Engagement Ring
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.