You will pay duties, PST and GST.
This adds to be a lot of money however less than having it seized.
A former client of mine purchased an engagement ring AND proposed to her in LA. She said "yes" and she had it on her finger when they came back to Canada.
Custom officer asked why were you out of country? She replied, we got engaged. Officer said "that's a pretty ring - where did you buy it?"
Yada, yada, yada. Total cost extra was an extra $3,000 that he had to pay. He was NOT happy. She told me that she couldn't stop crying.