Yellow and green is the most common of all tourmaline color varieties, but emerald-green is much rarer and more valuable. Indeed, until the 18th century it was often confused with emerald.
Emerald-green stones are found in Brazil, Tanzania, and Namibia; fibrous yellow material occurs in Sri Lanka.

Emerald-green stones are found in Brazil, Tanzania, and Namibia; fibrous yellow material occurs in Sri Lanka.
Yellow and Green Tourmaline Properties

