Cesium – $63,000/Kg

Found only in the US and Afghanistan, it would be easier to find this gem in mineral collections than in an ornament. It is so small that you would be lucky to get a piece weighing more than 10 carats, which explains its outrageous cost.

Cesium is toxic in its metal state. So, it is combined with different components and then converted through a hypothermal process to radioactive waste, an essential in the medical field. These rare stones have a colorless appearance, with simple maintenance requirements, needing no special care.