Kate’s Nizam of Hyderabad necklace

Finally, the most expensive royal jewelry piece on this list is the Kate’s Nizam of Hyderabad Necklace, valued at US$80 million. 

It is part of Princess Kate Middleton’s personal collection. However, the necklace is named after the Nizam of Hyderabad, a former princely state in India, and was presented to Kate Middleton as a gift. 

This necklace features a large oval diamond surrounded by smaller diamonds. Due to its historical and personal significance, as it has been worn on many special occasions by the Princess, it is the most expensive piece on this list.