What makes a quilt valuable?

I have inherited a quilt from my grandma that is somewhere between 100-150 years old. It is a thin quilt with simple stitching. Beyond that, I really can't offer anymore information. Is there more to the value of a quilt beyond age? I live in Indiana, would anyone know where to take a quilt to be appraised somewhere in the state? I am not trying to sell, just trying to figure out if I need to add to insurance, thanks.