Diamonds (and other precious stones) were usually foil-backed up till mid-19th century so that they reflected the light (stones weren't brilliant cut till quite late in the 19th century, and so didn't really 'sparkle' on their own). These old rings are GORGEOUS DA so . DO wear it and show it off as much as you can - they are pretty robust and shouldn't need cleaning if it isn't being worn for housework/washing up, just light dusting with a soft baby's toothbrush once in a (long) while.
Congratulations and enjoy!!