Citron
A source of confusion is that "citron" or similar words in French (and other languages), and English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name "citron" included the lemon and perhaps the lime as well.
Diamante citron
Genoa was known to supply citron for the Jews since the times of the Tosafists, along with surrounding municipalities Sanremo, Bordighera, and the rest of Liguria. The city is located in the region of Liguria, which itself has a long history of citron cultivation, thanks to the massive mountain chain (Apennines) which protects it from turbulent winds.