Can I antique a ring after I bought it?

I went to a pretty prestigious school. I always hated class rings but I did get a super simple signet ring that is great. It’s 18k gold and you really have to know the schools crest to even know what it is. Very under the radar.

My question is when I bought this I got it clean - no black around the engraving. Over time I’ve sort of regretted that. Is it possible to add the antiquing to the engraving or is it a lot cause?