So, after a bit of googling, I narrowed it down to these rings…
The Bulgari Griffe ring (Steve’s 1st choice)
The Cartier Ballerine Solitaire
The Cartier 1895 Solitaire with side baguettes
And the winner is…
The Cartier 1895 Solitaire with tapered side baguettes. It’s the composition that Steve likes, but I prefer the profile to the Bulgari Griffe and I think the diamonds on the side of the Cartier Ballerine distract from the centre stone, which in my mind should really be the hero.
I like this Harry Winston wedding band, emerald-cut baguettes, channel set the whole way around: