An example of a gem is an emerald.
An example of a gem is an excellent employee.
A little gem of a book.
A diamond is the hardest, most resilient, most beautiful gem of all.
The gem is protected by it.
The gem meant something to her.
Your goal is to steal a necklace with a red gem on it.
His eyes were brighter than the moon, greener than any gem she'd ever dreamt of.