Definition of Flan Bruni
In numismatics, the term "burnished blank" refers to coins whose blanks and corners have been polished before being minted. This process gives the coin's field a mirror-like appearance. Another term is "polished blank" or "mirror blank".
In the 19th century, burnished blanks were reserved for officials. From the 20th century onwards, they were intended for collectors.
It is possible that this quality is not intentional, and may appear by chance when corners are changed using particularly careful blanks. In the USA, this is known as "Prooflike", and in France as "quasi flan bruni".
However, although this expression is used today, no evidence of its use has been found in the archives of the Paris mint.