It depends on where you're located:
Australia — no. Exchanges are completely free, postage included both ways.
New Zealand — you'll need to ship your ring back to our NZ address (below), but we cover everything from there:
Suite 14033, Level 1, 6 Johnsonville Road, Johnsonville, Wellington 6037, New Zealand
All other international orders — you'll be responsible for the cost of shipping your ring back to our Melbourne warehouse:
6/25-37 Huntingdale Rd, Burwood VIC 3125, Australia
We recommend using a tracked shipping service for any return — we can't be responsible for items lost in transit.