The rarest gemstone in the world is considered to be ... For example, jadeite is the hardest natural mineral, and painite is the second-rarest mineral in the world. The rarest mineral in the ...

First discovered in 1902, gem-quality Grandidierite is extremely rare and is found only in Cap Andrahomana, Madagascar. Translucent specimens have also been found in New Zealand, Norway, and Suriname.