The picture is not 100% clear but it looks a little to me like counterfeit hallmarks.
The colour of the ring itself doesn't look to me like 18ct, it looks more like brass which has a plating which has subsequently worn off.
I may be wrong, but I would suggest you pop into your local jewellers and ask them to test the metal just to see.
Rating
Obliterated Jewelry Marks by: Jean
it reminds me of akhenaton of the 18th dynasty in ancient egypt. After Akhenaton's death, the priests of Amun chiseled in to power, restored the worship of all the old gods, and literally tried to chisel out the name of Akhenaton from history, this included chipping out his name on all the graven records, murals, and so on.
On your ring, except for the 18 mark - it looks like the other marks have been effaced. Makes you wonder what's wrong.
18K, 18ct or 750 (parts per 1000) or 75% gold. Most quality pieces are 18ct. It is the minimum gold standard for sale in Italy.
Have you tested the metal? It could be that the marks have been obliterated as the metal is not 18ct gold as it suggests. Could be plated. Just a thought.
