A Pedro I gold coin minted in 1822 is valued at $200,000-300,000 ahead of Heritage Auctions' January 5-6 sale.
The coin was the first to be struck in post-colonial Brazil, and was presented to guests at the coronation of the new emperor, Pedro I.
A member of the Portuguese royal family, who were living in exile in Brazil, Pedro I was a popular leader among the people. In 1832, he sailed to Europe to invade Portugal - dying of tuberculosis in 1834 after declaring victory.
Just 64 examples were created, with around 16 known to have survived to the present day.
Only two have been sold in the past 27 years, making this one of the rarest pieces of Brazilian numismatics.
The emperor was reportedly unhappy with the design, which portrayed him with a laurel wreath, and in the 1823 pressing he appears in full military uniform.
A gold solidus issued under the first reign of Western Roman emperor Priscus Attalus (AD 409-410) is valued at $200,000-240,000.
One of only two gold examples known, this is regarded as the finer example - featuring a clear strike on a round flan.
The solidus was minted in Rome following Attalus' emergency coronation in AD 409, when he was elected emperor by the senate after the incumbent emperor Honorius fled from the advancing Visigoths.
We have a range of rare coins available.
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