Cobalt Rings, Able to Resize or No?

OK, so I looked DEEEEEP into this exact issue awhile back. The basic story as far as I could find was that yes technically is is theoretically possible to resize cobalt... but good luck finding anyone who will actually do it for you. So effectively, no.

ETA: bonus tip - while the internet will tell you cobalt chrome is cheaper than white gold, actually finding such a thing is no small feat. I spent an inordinate amount of time looking for a simple 2mm cobalt chrome band in a small enough size for my finger, and when I finally found one it turned out to be more expensive than the same band in a more traditional metal. If you're choosing it for a non-cost reason, then I wish you much luck and hope you find exactly what you're looking for, but if you're choosing cobalt because of cost concerns, you may want to reconsider.