Sapphire Faceted Roundel

Grandidierites appear bluer in color the more iron (Fe) they contain. A recently discovered gemstone, blue ominelite, is the Fe-analogue grandidierite Grandidierites display strong trichroic pleochroism. That means that it can show three different colors depending on the viewing angle: dark blue-green, colorless (sometimes a very light yellow), or dark green.