Your ring is beautiful! Thanks so much - definitely helps put it in perspective.
The 1.53 is a higher G color than the 1.6 J (has your girl tried on a J colored diamond, there will be a yellow tint) I also don’t like the dark streak across the stone.
Here is the ASET comparison between the 1.6 and 1.5, both have pros and cons. The 1.5 has more red which means it’s going to sparkle like crazy but it also has some black which means there is a tiny bit of light leakage (I haven’t seen it in person but others have and all say they loved it), while the 1.6 has a lot more blue throughout the stone meaning the flashes won’t be as brilliant and again that streak really bothers me.
For me the 1.53 and 2.01 are cut better than the 1.6, I like the 2.01 I color over the 1.6 J color (I color is safe for people who not color sensitive but it’s a larger stone so you might see slight color warmth in some lighting; also this is a far cry from the D/E/F you were first wanting). Lastly for the 1.53 I like the G color (will be white diamond) and even with it being Si1 the people who have seen it in person all say it is eye clean.
I still think it’s between the 1.53 and 2 ct., but then again 4K is a big price jump and that 4K could be spent on the setting instead. Can Jon not get a video comparing them all together? Also I’m wondering if he can send them to an appraiser for you to look at in person? Sometime people have had that done, they have diamonds shipped prior to purchase to view to a mediator and then whatever stones are rejected get sent back to the dealer.
Preowned is not a big deal
MollyMalone - such a gorgeous ring. Is it yours?
Top down view is classic but basic (everyone is doing them and you really cant mess it up) but the side view I dislike, the basket in my opinion is way too high (cathedral look that is either you like it or hate it kinda of thing).
SO in saying that what your lady tried on and liked? What type of work, activities, hobbies does she do, this is important since a high set diamond can get knocked around in certain situations. Also does she have a desire over how the wedding band sits (does she mind/like the gap between rings or wants a flush finish)? I know this may seem like a lot of questions but don't stress! This is the fun part