I got my wife a moissanite and it turned out beautiful.
She likes big stones so I got her a 2ct oval one which she loved. Didn’t care much for the technicalities - it looks good, suits her style and that’s all that matters.
And no way you could get a 2ct diamond for 700$.
A person who won’t appreciate how you choose to express your love isn’t someone you’d want to marry, anyway.