No, the police clearance certificate does not have to be stamped by embassy or consulate.
It is a certificate based on "name search" (CAD 35. +/-), as opposed to "fingerprint search" which is much more expensive to produce.

When you're dealing with an employer, you do not take verbal instructions. You ask your questions in writing and you request written answers. In your case, you should have a written list of documents that your employer expects to receive from you: copies of degrees, marriage certificate, police clearance, etc.etc.

I don't want to confuse you but i have also heard that QP is not asking for police clearance any more? may be just a rumor. Get the required document list from QP/HR, then proceed.

Good luck !

Moudir