I had an F stone with medium blue for 25 years and didn't know it had it until a jeweler mentioned it when I was considering a reset. There are no concerns with medium fluorescence. You'd have to have the ring directly in UV lighting to see it.
Thank you, Gadabout! Realistically, pictures don't show color well or things like fluorescence unless we shine a UV light on them! So the value is somewhat limited as compared with seeing for yourself!
I have a GIA E with medium blue fluorescence and saw clear blueness in it once on a very sunny day in the mountains where light was reflected from snow, too. Otherwise on sunny days I see (or imagine) only a hint of blueness in direct sunlight and sometimes wish the fluorescence was stronger