It is unclear whether your are visitor or immigrant. About the latter, the website of the Goverment of Canada states:
Bringing goods to Canada
When you move to Canada from another country, you may bring your personal and household goods with you without paying duty. You’ll have to pay duty on any item you bring that hasn’t been used.
You don’t have to pay duty on . . . jewellery
and further on
Jewellery or precious ornaments
Officers may ask you questions about your jewellery or precious ornaments during your customs interview. Make sure you describe these items on your list of goods. To avoid delays at customs when you enter Canada:
- use the wording from your insurance policy or jeweler’s appraisal on your list of goods
- include photographs of the items
- know how much you paid for the items or have a receipt showing how much you paid
- you don’t need to pay duty or tax on family heirlooms
About your question, it does seem advisable to have your jewellery valued. If you have travel insurance it might be needed for that too.
Readers have pointed out that the above information is directed to immigrants, and OP now clarifies they are a visitor. So I explored a bit and found the Government of Canada web page Visit Canada has a list of topics. The most relevant of those is Border information for international travel
On this page there are two relevant links:
a) Estimate duty and taxes but this is a form related to things you have bought, not family heirlooms.
b) Bring Goods Across the Border but this begins with "When you return to Canada ..." so it is for residents.
None of those links answers your question, so I suggest you use the Contact border information services link provided.