Who is the most expensive crown?

Can you enlighten me on the question of which crown holds the title of being the most expensive? Is it a historical artifact adorned with rare gems and metals, or a modern creation crafted with unparalleled intricacy and value? What factors contribute to its exorbitant price tag? Perhaps it's a piece of royal heritage, passed down through generations, imbued with immeasurable sentimental worth. Alternatively, could it be a one-of-a-kind masterpiece, crafted specifically for a noteworthy occasion or individual? I'm intrigued to know more about this enigmatic crown and the secrets that lie within its opulent exterior.