Tumbled stones are gemstones where the grinding / polishing process is similar to how nature does, when stones roll down from the mountains.
They often ended up in a river and then are again ground by water, gravity and contact with each other, to how they are eventually found by humans. This makes each tumbled stone unique, because they are not cut with human hands.
I have tumbled stones in stock in different sizes, the size is measured on the widest / thickest / longest length of the relevant gemstones.
You can find them in the left menu (in mobile shop at the bottom of the page) per size.