I purchased a gold tremissis , Maurice Tiberius from a local Auctioneer approximately 2 years ago, I just accepted that it was a genuine coin. I decided to sell it on and advertised it on eBay. Someone queried its authenticity which prompted me to weigh it. It weighs between 1.1 and 1.2 grams. All the examples I find online weigh between 1.4 and 1.5 grams. Have I purchased a fake coin or could it be genuine?