Answer:

spinel

Answer	Crossword Clue
SPINEL	Rubylike gemstone
SPINEL	The Black Prince's Ruby is one
SPINEL	Mineral used as a gem

SPINEL	Red gem.
SPINEL	Kind of ruby.
SPINEL	Ornamental stone
SPINEL	Ruby variety
SPINEL	Ruby ... (gem)
SPINEL	Crystalline gemstone
SPINEL	Rubylike gem
SPINEL	Mineral containing magnesium

SPINEL	Reddish mineral