Color in Gems and Minerals

We will treat color separately for the different minerals and just add a few notes here the importance of dopants is clear from Table 36.5. There are several different causes of color in gemstones. Most are associated with local trapped charges. [Pg.660]

Cobalt Synthetic blue and green spinel, synthetic blue [Pg.660]

Nickel Chrysoprase, synthetic green and yellow sapphires [Pg.660]

Copper Diopside, malachite, turquoise, synthetic green sapphire [Pg.660]

FIGURE 36.13 (a) Illustration of the combined effect of incorporation of Ti and Fe in sapphire. The distance between the dopant cations is 0.265nm. (b) The corresponding energy band diagram for the excitation showing how a gemstone with blue coloration is obtained by absorption. [Pg.661]

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