Question: what are the rare gemstones?
Answer: TANZANITE // FOUND ONLY IN TANZANIA. ...  BLACK OPAL // THE DARKER THE BETTER. ...  PARAIBA TOURMALINE // NEON LUSTER. ...  GRANDIDERITE // ONE EXCEPTIONAL EXAMPLE. ...  ALEXANDRITE // COLOR-SHIFTING GEM. ...  BENITOITE // STATE GEM OF CALIFORNIA. ...  PAINITE // ONCE THE WORLD'S RAREST GEM. ...  RED BERYL // TINY AND SCARCE.