I would be very suspicious of a Roman coin that was dated 125 BC. After all, the Romans did not use Arabic numerals.
Lissen up, the Arabs don't use Arabic numerals neither. Your rude questioning of this precious heirloom's authenticity made me so angry, that I slammed down my Obama Commemorative Drinking Mug on my Commemorative Obama Plate and not only chipped it, but I got Java-Obama all over my Obama Teeshirt, the Obama blanket around my shoulders, and the Obama throw rug.
Furthermore, Buster, The Neapolitan antique shop guy told me the Romans ALWAYS used those numerals on your smaller genuine BC Roman coins, as all of them XLICMV thingies wouldn't hardly fit so good, now would they? Plus who the heck woulda been able to figure out the date?
I would guess the date was numbered counting forward from the founding of Rome(about 753 BC), AUC (ab urbe condita).