At Paraiba, a new variety of tourmaline was found that derived its color from minute amounts of copper and gold. The combination of these two trace elements yielded a medium-toned (forty-five to sixty percent) blue to green gem of unrivaled saturation.

Traditionally, blue and green tourmaline has been graded using standards borrowed from ruby, sapphire, and emerald. Darker-toned stones (seventy-five to eighty-five percent) have been the most sought after.

However, the hottest Paraiba colors are not sapphire-like or emerald-like dark primary hues, but vivid pastel hues in the blue to green range with tonal values between forty-five and sixty percent. Terms like “neon,”
“Caribbean blue,” and “electric green” aptly describe the gems of Paraiba. Within a year of the discovery, prices of Paraiba stones over a carat escalated from several hundred to several thousands of dollars per carat, prices that would have been unimaginable just a year before. Paraiba produced darker-toned (eighty to eighty-five percent) stones with a seventy-five percent primary hue of blue and a twenty percent secondary hue of green that resembled sapphires from Australia and Thailand. These stones, among the rarest and most sought after tourmaline variety, the so-called sapphire-blue indicolite, were promptly heat treated. Those that turned a lighter-toned neon blue greatly increased in value.
Unfortunately the San José da Batalha mine was mostly exhausted within a few years but not before the tourmalines of Paraiba already had passed into legend.
The effect of this discovery was twofold: first, it focused attention on tourmaline and established a tourmaline aristocracy, giving the gem something it had previously lacked: snob appeal. Secondly, attention was shifted from the ruby-sapphire-emerald look-alike standard to a new appreciation of so-called Paraiba look-alikes. That is, medium-toned stones in the blue to green hues earned a new respect. Finally, tourmaline began to emerge from the shadows and to be appreciated for itself, as an important gemstone beautiful and valuable in its own right.

A few reddish purple stones were also produced which, due to their rarity, have not been given much attention. Blue Paraiba stones, which are more highly saturated and do not have the gray mask, might be described as a sort of “neon-aquamarine.” A visually pure blue between fifty and seventy-five percent is the most desirable.
Green Paraiba stones resemble a more vivid version of the lighter tones of emerald traditionally associated with the Nova Era area of the Brazilian state of Minas Gerais. Green Paraiba tourmaline, the finest of which is a visually pure green between fifty and seventy-five percent tone, sells for substantially less than the blue variety.