Antique silver ring with hidden container

An ancient Mexican ring made of sterling black silver with stamps, a breakdown and a lilac stone in the shape of a cabochon, similar to amethyst or kunzite, but perhaps it is an artificial stone. The ring has a very interesting shape, well-fitting to the finger, it is made by an old master manually with great attention to all the smallest details. The top part with the stone is thrown back, revealing an oval container (previously this hiding place was called a place for storing poison), the container is closed with a click. This antique ring is dimensionless, which makes it possible to wear it at will on different fingers, and it is in excellent condition.