Does the stolen amethyst have a curse?

From the article:

Three years after his death in 1943, as he’d instructed, his daughter unlocked the amethyst and gave it to the museum. It was accompanied by a letter that cautioned against the lilac stone’s history of evil, reportedly reading: “Whoever shall then open it, shall first read out this warning, and then do as he pleases with the jewel. My advice to him or her is to cast it into the sea.”