Transition elements that cause color in gemstones and the spectra produced by
them
Chromium:
Chromium has broad absorption on the violet and green areas of the spectrum. It also
gives narrow absorption bands in the red area.
Chromium is found in the following gemstones:
Green color: Emerald, jadeite, alexandrite and demantoid garnet.
Red color: Spinel, ruby and pyrope garnet.
Cobalt:
Cobalt gives three absorption bands in the green, yellow and orange regions of the
spectrum.
Cobalt is found in the following gemstones:
Blue: Glass, synthetic spinel and synthetic blue quartz.
Copper:
Usually does not give any absorption bands. However there might be very faint
absorption in the blue region of the spectrum.
Copper is found in the following gemstones:
Blue: Turquoise, chrysocolla and azurite.
Green: Dioptase and malachite.
Iron:
Iron gives broad absorption bands in the blue-green areas of the spectrum.
Iron is found in the following gemstones:
Blue: Spinel, aquamarine and sapphire.
Green: Tourmaline, sapphire and peridot.
Red: Alamandine garnet.
Yellow: Citrene and chrysoberyl.
Manganese:
Broad absorption bands in the blue and violet regions of the spectrum.
Manganese is found in the following gemstones;
Pink: Kunzite, rhodonite, morganite and rhodochrosite.
Nickel:
Does not usually give absorption pattern.
Nickel is found in the following gemstones:
Green: Prase opal and chrysoprase.
Rare Earth (Neodymium and Praesodymium) :
These give several sharp bands in the yellow region.
These rare transition elements are found in the following gemstones:
Green: Sphene
Yellow: Danburite and apatite.
Titanium:
Absorption is with iron in the blue region.
Titanium is found in the following gemstones:
It usually occurs with iron.
Blue: Benitoite and sapphire.
Vanadium:
Weak absorption in the green and blue portions of the spectrum.
Vanadium is found in the following gemstones but usually play a secondary role in
determining the color of the gemstones:
Green: Beryl, color changing sapphire, tsavorite and tanzanite.