Tourmaline is a birthstone for October. Here is a bin of raw, unpolished green and yellow tourmaline crystals. Emerald green is the most valuable of all the color varieties. In fact, often it is mistaken for emerald. This green gemstone is mined from Brazil, Tanzania, and Namibia, while the yellow gems come from Sri Lanka. Here, a mix of raw stones are bundled into bins for selections. Their raw straitions invite my imagination. Tourmaline's name comes from the Sinhalese tura mali , which means "mixed stone." Tourmaline lives up to its name.