A jade ring is cut from a solid core — a cylinder is drilled out, then ground on the outside and the inside until the band is even. There is no soldering, no sizing and no repair, so the fit must be right when it is made.
Nephrite is one of only two minerals properly called jade, and its interlocking fibre structure means a band this wide and this thin will flex slightly rather than shatter if knocked. Measure the knuckle, not the base of the finger, and allow for a slight taper if the finger changes size in the heat.