don't know if the link will work, but it's the Ranelagh dress.
I have been searching (though, I do still have three months til the wedding), and this is the best contendor so far.
It's going to be in July in a hot country, but will be indoors in the air-conditioning. I'll need to cover my arms as they're ming, so may need suggestions for that. I was thinking of wearing it with nude satin shoes and carrying a sparkly gold bag.
Is it evening-y enough? I'm 29, I am concerned that it might be a bit old.