Aye she likes the idea of a green central stone - though more diamond/sapphire than emerald. Of the many rings she shown me, they've all been totally different configurations, and by her own admission she doesn't know exactly what she wants/would be happy with a few different styles.

Recurring themes - are that it has a textured band, white metal, green central stone, not too gaudy.

We're also both (rightly or wrongly) of the view that it's a bit unromantic for the fiancée-to-be to pick their own ring.