Gerard van Loon

correspondent, neighbor, and intermediary for medal from faculty at Leuven
Birth or Baptism date: 
January 17, 1683
Death or Burial date: 
August 29, 1758

His family owned the extensive bewery, the Verkeerde Wereld, on the east side of the Brabanste Turfmarkt. Van Loon was educated at Leuven, where he was a student of the Jansenist Antony Cink, and at Leiden.

He was a lawyer and numismatist who wrote several historical studies, including in 1731 a comprehensive, illustrated study of Dutch historical coins and medals that is still a standard reference work, Beschrijving der Nederlandsche Historiepenningen, 4 volumes ('s-Gravenhage, 1723-1731).

In 1716, Leeuwenhoek addressed one of the Send-Brieven to the 32-year-old Van Loon. It was about hops, a topic related to both of their families. It is dated a month before Leeuwenhoek received a medal from the faculty at Leuven, handed over to him by Van Loon in the presence of Delft notary Jacob van der Werff.

The close-up on the left (click to enlarge) is a detail from a portrait by Jacob Houbraken.

wikipedia nl

Van Loon was one of the executors of Leeuwenhoek's estate.