I can show you the rings I'm finding.  It's actually really fun to think about, because you gotta think about the time period, their economic status, the girl's taste, and, super interestingly, what their 'husband' would pick out for them.  It's about the girl's taste, interpreted through their 'husband's' eyes.

There's also this great thing called posy rings, which was a thing in the middle ages.  Posy is supposed to be prose, as in poetry, so it's all these engagement and wedding rings with little love poems engraved inside.

So these are what I imagine Elizabeth's 'wedding' ring looks like.
[img]https://67.media.tumblr.com/d964108c15af2ced15fa6586bd6a417f/tumblr_ofvh3fmPnq1sk9phao1_250.jpg[/img]
[img]https://67.media.tumblr.com/e66e372e864015e98653e0564773a04b/tumblr_ofvh3fmPnq1sk9phao2_500.jpg[/img]

This would be Nadya's - the inscription says 'In thy sight is my delight', which I figure works for something Bela would give her.
[img]https://68.media.tumblr.com/bb89abcfbf4af7cae103bcd714e598fe/tumblr_ofvh3fmPnq1sk9phao4_500.jpg[/img]

And Eleanora's.... oh, that was a good time.
So of course she'd want more elaborate rings.  And she'd really want color, as many ladies did then.
[img]https://66.media.tumblr.com/4c196facb2a58356861153481024e343/tumblr_ofvh3fmPnq1sk9phao5_1280.jpg[/img]
[img]https://66.media.tumblr.com/994c795e3ce0a4d4a4dcf77b1455a4a8/tumblr_ofvh3fmPnq1sk9phao6_1280.jpg[/img]

And then it makes it all the cuter and kinda sadder when Jonathan gets her this very simple but very sincere  ring
[img]https://66.media.tumblr.com/809bfb77bfad91c2b7e772deab64be2f/tumblr_ofvh3fmPnq1sk9phao8_500.jpg[/img]
It says 'In love abide till death divide'
(I hereby nominate Jonathan Mercer as the designated cinnamon roll of this story)

So this was a really fun study in jewelry trends of the 14-17th centuries and how these couples really relate to each other.