#4 was the rounder one on the left in your first photo, right? That is also very nice. It's pinker. You mentioned on your other thread that you wear pinks and blues.
#1 is the one on the right in the first photo, correct? It will face-up larger (look larger when you look down on your hand), and won't protrude as much since it is a little flatter, judging from the first photo. It isn't way-off-round, though, and has interesting colors.
So:
#4 is larger in total size, rounder and pinker.
#1 looks larger when you look down at your hand but protrudes less and is less round.
# 4 is more standard (while still being an amazing gorgeous pearl!) in that it is round and a more uniform color.
# 1 is more unusual-- interesting shape and color overtones.
Considerations:
• Do your rings tend to spin? A pearl that protrudes more may spin more. (But I suppose it couldn't spin far in any case, with such a huge pearl.)
• How large is your hand? A pearl that faces up larger may look too large for a petite hand. (But again, both pearls are large so if you can wear one, you can wear the other.)
• Are you looking to wear a conversation piece? Which one would do that for you?
• #3, the lavender one, would go great with the cooler lavender FWP, if those are what you buy. And #4 the pinker one would go well with the warmer lavender FWP, if you buy those. Not that matching a ring with strands matters.
Sorry but to me #2 is boring.
I think you may be leaning toward #4. If so, go for it! It's a great pearl and you can't lose.
Edit: I just read your post about choosing the warmer lavender pearls. Then #4 would go very well with them.
But you know, really just pick what you like! You're the one wearing it!