Finally, gemologists who studied the material concluded its colors were, for the
most part, natural—the product of the trace element copper. We say “for the most
part” because Brazilian dealers admit heating some sapphire-blue, as well as
gray and dark-green stones, to render them spectacular turquoise and tsavorite
hues.
Paraiba’s palette
When dealers first saw samples of the new-find tourmalines in early 1989, the
vibrant colors left them as much in awe as in doubt. Dealers thought that colors
that vivid couldn’t possibly be natural.
Given the possibility that a significant percentage of pink and red tourmalines
are irradiated, stones from Paraiba were bound to trigger trade skepticism.
Endowed with colors that evoked comparisons to peacock feathers and tropical
fish, the colors just seemed to good to be true.