The Florentine Diamond was the heirloom of the Medici family of Florence. The diamond went missing sometime after 1918 when Charles 1 of Austria went into exile following the collapse of the Austro-Hungarian Empire. The whereabouts of the diamond remain a mystery to this day.
Alaric’s treasure is the riches the Visigoths buried with their king after they looted Rome in 410 CE. Tradition claims that the Visigoths buried Alaric under the riverbed of the Busento with the riches, but the location remains a mystery.
The Amber Room was an ornate chamber at the Catherine Palace in Tsarskoye Selo (Pushkin) near Saint Petersburg. It went missing during the Second World War after the Nazis stole it from the Catherine Palace and reinstalled it at the Königsberg Castle.