Gold and sapphire ring

This ring was in a lot I bought some weeks ago. At first I didn't really like it but now I have been wearing it a lot lately and I just started loving it.
It's 18K yellow gold with a navette -shaped sapphire and surrounded by old cut diamonds. The diamonds are mounted in silver or white gold.
Although it is tested 18K gold, inside the ring it says 470...Does anyone have an idea what that could mean?
I think navette-shaped stones were popular in the victorian era. So what do you think about the age of the ring?
Thanks a lot!