Venetian Gold Coin? ID + authentication Help

Hello all recently acquired this gold coin which I think is venetian medieval. It weighs 3.5 grams and roughly 20mm diameter. Is it authentic? What exactly is it? Thank you in advance! 

The legend on the obverse between 12:00 and 6:00 reads NICOL TRONVS, so we know this is the zecchino (ducat) of Nicolo Tron.

N#116369

Authentication is not possible from a photo (and is above my pay grade 🙂), but if you didn't pay upwards of 5000 euro, the coin is likely not authentic. 

https://www.numisbids.com/sale/7287/lot/?lot=430

Thank you very much for your time, much appreciated 🙏