Welcome to Tnet.
It’s a nice ring, but I find this a little odd. I don’t immediately recognise the marks, which I suspect are relatively modern but I think this ring must have been made outside the USA but sold within it, or vice-versa… depending on whether the 10K mark was applied before or after the 375 mark.
In the US, 9K (375) purity doesn’t qualify to be sold as ‘gold’ (not since 1906 anyway) but it’s a common minimum standard in many other countries. However, in those countries with a 9K (375) standard, a 10K purity ring could only be marked as 9K. So, it could have been made and marked as 10K in the US and then re-marked at 9K (375) to align with the standards of a country outside the US where it was sold. Or, it could have been made at 9K (375) outside the US and someone has ‘upgraded’ it to 10K to meet the minimum US standard for gold. If the latter, that may or may not have been a legitimate upgrade for the mark. There can be a bit of tolerance on composition such that a ring made to a nominal minimum of 9K might just scrape into 10K.