An item that puts a horible curse on the victims of its spell.
A dark emperors gloves that make an excelent weapon and torture tool.
Elementalist have commonly used jems to further their powers over nature.
What if the sources of precious metal in the realm all failed, so that the only sources for gold and other precious metal were hostile foreign lands? Gold coinage might become increasingly rare, resulting in hoarding. Player characters that appear with masses of treasure might be suspected of being in the pay of foreign powers.