Certification ID verification

Please answer if anybody gets any idea on it:

How can we verify if a consultant is indeed SAP Certified? I know there is a certification ID  being granted to a SAP Certified professional. Can we check if the certification number is authentic. If there is a certification number, Is there a list or website to view the details of that SAP certified consultant. Or is this something we can request from a SAP office to check if the certification number or certificate is real?

Thanks,

-Su