I do realise its almost a year since the last post on this thread, but since I'm new here, I'm only reading it for the first time. So.....? is the problem solved?
Nerida has seen my pearl cage ring in the flesh, & whilst its very 'contemporary', and not really meant to be an engagement ring, here 'tis. You can see the pearl can be very easily replaced, in fact, it is only held in place by the wearers finger! Perhaps not too practical for every day use, but great to change the colour of the captured gem to match an outfit.
I am now very self concious of showing my pearls here, when I bought them, I had such limited knowledge, so I chose on my own most desireable criteria: lustre, (and of course, what I could afford at the time...)