How do I tell if my Toner Cartridges are Genuine Canon toner cartridges?

[muhlb]

How do I tell if the Toner I have in my possession is Genuine Canon toner and not a knock off?  I have an MF733Cdw laser printer with 046 toner cartridges.  I do not recall where I purchased them from but I want to verify that they are genuine.  There appear to be QR codes on the cartridges

[shadowsports]

See this:

Canon U.S.A., Inc. | Supplies Product Information

[muhlb]

I found this which seems to be what I'm looking for http://downloads.canon.com/nw/industries/GPR_22_Toner_Counterfeit.pdf

However it seems that the basis by which "genuine"-ness is determined is through the markings on the box, which I threw away long ago.  Ideally I was hoping there would be a serial number on the actual cartridge that I could look up

[philb001]

It would be very nice to know how to tell if a cartridge is genuine. The markings on the box are obviously not foolproof and could easily be faked. The cartridge itself saying Canon is no good because it could presumably have been refilled with alternative toner.
Also what is the exact weight of a full toner cartridge? The last "genuine" high yield cartridges I bought through Amazon lasted less than 100 copies and no they were not all solid colors.
Does Canon take any interest in this kind of fake.