Not really; if the ring was bought in the U.S., she would - as a Canadian citizen - be charged for importing it to Canada.
If the ring was bought in Canada there wouldn't have been any taxes at all as it would not be considered imported in the first place, but I'm guessing that's not the case - which is also why the form you mentioned (although it's generally very smart, useful and awesome

) wouldn't help here since it only prevents taxation of domestically bought (or already taxed) goods when returning to your country; my understanding in this case is that OP's wife went to the States with no ring and came back with one.
210045803, could you please clarify where did the ring come from and how many times has it crossed the border?
Oh, and regardless of all that? Mister officer was still a giant ******bag.