Hope this helps.
http://www.ccra-adrc.gc.ca/E/pub/cp/rc4044/rc4044-01e.pdf
Protecting your valuables
Before travelling abroad with valuable items, you can take advantage of a free identification procedure at any of our customs offices. This service is available for items that have serial numbers or other unique markings. For items that do not have such markings, we can apply a sticker to give them a serial number.
When you show your valuables to the customs officer and state that you got them in Canada or lawfully imported them, the officer will list your valuables and their serial numbers on a wallet-sized card. If you are questioned about your goods when you return to Canada, simply show your card to the customs officer. This will help identify the valuables that were in your possession before leaving the country.
Jewellery
Because jewellery often has significant value and can be difficult to identify, we cannot list it on this card. We suggest that you travel with as little jewellery as possible. Taking the following steps before you leave Canada will make it easier for you to re-enter the country with jewellery.
Get an appraisal report from a gemologist, jeweller, or insurance agent, as well as a signed and dated photograph.
Get written certification that the items or jewellery in the photograph are the ones described in the appraisal report.
Carry the appraisal report, the certified photograph, and a copy of the bill of sale when travelling abroad. If you imported the goods previously, make sure you have a copy of your customs receipt.
Modifying an item outside Canada
Under customs law, if you take any item outside Canada and change it in any way or make it more valuable, we do not consider it to be the same item when you bring it back into the country. You have to declare the full value of the new item.
Example
You take an old diamond ring with you on a trip outside Canada. While abroad, you replace the diamond. When you return to Canada, we consider the whole ring to be new.
Even if part of the ring is made from Canadian material, we have to treat the ring like any other piece of jewellery you got outside the country. This rule applies unless you have previous authorization from us to have those repairs or alterations made abroad.