Answer: spinels

AnswerCrossword Clue
SPINELSRubylike gems
SPINELSCertain gemstones
SPINELSMinerals used as gems
SPINELSRed gemstones
spinelsSPINEL, a mineral, also SPINELLE
spinelsAny of a class of oxides including this, containing aluminum and another metal and having the general formula MAl2O4
spinelsA hard glassy mineral occurring as octahedral crystals of variable color and consisting chiefly of magnesium and aluminum oxides