One of the most interesting of the commercially available Czochralski pulled synthetic corundums is pink “Ti-sapphire.” This material owes its pleasant, somewhat orangy pink color to trivalent titanium, a common trace element in natural sapphires and rubies that occurs here in an unusual oxidation state. Although most of the gemological features are typical of Czochralski-pulled corundum (gas bubbles or small "pinpoint” inclusions, color zoning), these synthetic sapphires have distinctive fluorescence and optical spectra. These properties are also due to the chromophore Ti3+.
