A ring should only be sized as far as suggested in the pieces listing, on pieces with stones set into them this is non negotiable.
Rings with stones cast in place cannot be sized.
Some things to consider before having a ring sized
To size a ring up 1/2 a size I can gently coax it up with a hammer, anything other than that I am adding or removing a piece of the ring which will effect the ring in several ways, most importantly it will leave a solder line, and it will effect the proportions of the ring.
Crag rings in particular should not be sized more than 1 size, even 1 size can be dramatic to the proportions especially in the smaller sizes.
With the Plateau rings more than one size up or down and the proportions start to look off to me.
If a piece is sized for you it is Non-Refundable.
If you are buying multiple rings and sizings make sure to clarify in the notes in the cart at checkout, or send an email with your order number and what rings you want with the sizing purchased.