Probably not natural stone
This does not appear to be natural or undyed tourmaline. This listing states the stone is tourmaline. I have several natural verified gemstones and the color of this stone does not match the price (dark green which runs $60-100.00 per karat). There is also no variation in color which would be expected. I looked on the main website for the seller which does not list tourmaline as a natural stone they sell. I do not believe this to be authentic tourmaline. I would have been much happier with a natural stone which would have most likely been truer to the picture color (pale green) with some variances. One star because the product is well made. One star because it is a nice size and meets the price for an unnatural stone in sterling silver. I will be returning this product.
Rating: 2 stars