Sapphire is the second gem variety of corundum after Ruby. Sapphire displays the maximum variety of colors among all precious gemstones, varying from a range of blue, known as Blue Sapphire to pink, known as Pink Sapphire & all the way to white, known as White Sapphire.
Blue sapphires contain trace amounts of vanadium and come in a variety of shades. Corundum that contains ~0.01% of titanium is colorless. If trace amounts of iron are present, a very pale yellow to green color may be seen. If both titanium and iron impurities are present together, however, the result is a magnificent deep-blue color.
Unlike localized ("interatomic") absorption of light which causes color for chromium and vanadium impurities, blue color in sapphires comes from intervalence charge transfer, which is the transfer of an electron from one transition-metal ion to another via the conduction or valence band. The iron can take the form Fe2+or Fe3+, while titanium generally takes the form Ti4+. If Fe2+ and Ti4+ ions are substituted for Al3+, localized areas of charge imbalance are created. An electron transfer from Fe2+ and Ti4+ can cause a change in the valence state of both. Because of the valence change there is a specific change in energy for the electron, and electromagnetic energy is absorbed. The wavelength of the energy absorbed corresponds to yellow light. When this light is subtracted from incident white light, the complementary color blue results. Sometimes when atomic spacing is different in different directions there is resulting blue-green dichroism.
Star Sapphires: Star Sapphire is a rare variety of Sapphire that exhibits asterism. Star Sapphires shine with six rays of light ideally converging towards the centre.
Our sapphire jewelry collections are available at Sapphire Jewelry by Jewelove™.