Thank you and fanned you. The ring is actually a Sarah Coventry ring with a Copyright stamp proceeding the stamp SARAH COV. in which you can see from this link it is authentic http://www.illusionjewels.com/costumejewelrymarksc.html and the band is fixed to adjusted to fit any size.
I am not sure of the size. However it is a Sarah Coventry ring and is stamped with a copyright mark preceding SARAH COV. in which you can look at this link to show that it is an original mark. The band is however fixed so that it can be adjusted to fit many sizes. http://www.illusionjewels.com/costumejewelrymarksc.html