At the moment I've got a 5 Sapphire and a 5S non-Sapphire, so I thought I take a couple of photos to show the display difference in terms of resolution and clarity before one of them goes back.
I've posted the photos here: https://www.dropbox.com/sh/64vnksruik27pyh/AAATdyH7CaqeDkiIuQvxUE7Ta?dl=0
Only quick shots, but hopefully enough to illustrate the similarities/differences.
I've not labelled the photos, but the ones with the black bezel are the f5, the silver bezel the f5S
Resolution-wise, I'd say you'd be hard-pressed to notice any difference - the 0.1" difference in display size isn't really go to make the difference between being able to read something or not, and the lower pixel count doesn't seem to be evident - the increased number of colours over the f3 probably helps here.
What is quite surprising is how clear the standard glass is compared to the sapphire. When you see the sapphire on its own, you don't notice anything, but up against the glass you realise just how much less transparent the sapphire is. In real life it still appears clearer than the photos, you don't see the almost tinted effect that the photo shows, but what you do notice is just how much dimmer the sapphire display is compared to the glass one (all these photos were taken without the backlight on)