I'm pretty sure it's a wedding ring in the first picture, and that the date of very early 1880s is correct going by the clothing and pose/framing etc.
The second picture I thought was from about 1880 as well, as she is wearing a dress with a long, flat front (curiasse bodice), gathering at the top of the skirt and not much in the way of the embellishment we see from the 1870s.
I also agree with Jim that she's probably about 16 - her skirt is too short for this to be a 'grown-up' picture, and her hair being worn down also indicates that she is a young girl.