You can. But with jewellery - because it's hard to identify and border officers are not experts when it comes to it, and it's not unique but people don't really want those stickers on it - you can't put it on the Y38 form unless you previously obtain an appraisal report together with dated photographs of the item and original receipt, if applicable. Which is a lot of trouble and costs money, although it would make sense to do if you travel frequently with a single piece of jewellery. (Y38, they tell me, is a smallish thing easily fit into one's wallet.)
However, useful info: customs-working friend tells me that most jewellers at the airport can do an appraisal for you on the spot and customs will accept that as sufficient proof for temporary exportation. So if you ever remember this at the very last minute... well, do the responsible thing
I'm still very curious about the by-the-book aspects of this, though. It's true that people say all kinds of things to get off the customs hook, but in this particular case the officer checked with the husband who admittedly bought the ring, and then merely took his word for its value... and then someone else paid the fees *scratches head* Unless there is something the OP is not telling us, of course.
Hey, I could do that next time I file my taxes! Won't even bother with the forms, just write a nice note. "Dear government, last year I made 35,000$ and had 20,000$ of daycare expenses for my child. Since this is how taxes are done in Canada, please give me back eleventy bajillion dollars without any type of proof. Or maybe you could make the daycare pay me back, since they caused the expense in the first place? Whatever works for you. Thanks."
See, who ever said taxes have to be hard! *end of sarcasm*
