Telefunken in Disguise?

A highly rated Audiogoner sold me what are supposed to be a pair of Telefunken 12au7 smooth plate tubes. What actually arrived were tubes labeled "Mazda BelVu 12au7  ECC82." They do have what appears to be a diamond engraved on bottoms, although it is hard to see. He insists these really are Telefunken - made 12au7 smooth plates. I do not know enough to accept or not. I cannot find anything on-line confirming his representations.

What say the the tube experts?

Tele’s diamond is actually an embossed(raised/molded) emblem, rather than engraved. If it doesn’t appear as shown in these pics- the tubes aren’t genuine Telefunken:
Thanks, Rodman. I may have used an inexact term. I will check them again, and perhaps post a photo.

There are Telefunken smooth plates that have Mazda labels and they should have the diamond embossed.  That could be what you have.
Be carful  i once got Telefunken that sounded like junk hope you did not pay to much and they sound good.Good luck.

There are a LOT of re-branded Telefunken tubes out there (as well as loads of counterfeit ones).

Here are a couple of links that might help:
On counterfeit you can make fortune especially on ones that have no compromise in performance to the original. I once had Dr. Dre beats studio purchased for $12 sounded and looked exactly the same as $250 ones. When Alibaba wasn't US owned company, it was HEAVEN -- no labor needed -- just buy and sell.
Very often I noted counterfeit is just the same product, but manufactured voiding customs, taxes, commercials... another words just product without too much of third parties. Every dark side indeed has bright one as well.

Beware these tubes could be a phony ripoff!!

The Tubemonger Library, a great resource for identifying tubes has a couple of pictures of Telefunken 12AU7s labelled Mazda Belvu here:

If yours have the diamond on the bottom and look like the ones in the photos, I'd say they're Telefunkens. 

ebm, I too have a few "Telefunken" tubes that sound bad. However, of the 16 best 6922's I have ever heard, 16 are Telefunken. That includes US Amperex (including pinch waist), Dutch Amperex, Siemens, etc. 
If they were actually Mazda/Belvu tubes, then they might actually sound BETTER than Telefunkens. E.g. with 12ax7 types, I easily prefer the Mazda chrome-plate over either Telefunken variant, and Mazda tubes in general tend to sound pretty damn good (they also made a really nice chrome-plate 12au7). The French performance in WW2 was less than stellar, but they certainly made some fantastic tubes for phoning in "we surrender!" loud and clear!

Relabeling/rebranding in the tube era was extremely common, and careful inspection of construction is your best bet for properly ID’ing the actual make/vintage of a tube. Use online pictures as a reference until you get more familiar with actual tube examples. The seller is not liable to provide tubes wearing any particular label (or ANY label at all), unless they specify labels prior to sale, or you specify that you’re picky about labels.

As far as your Teles go, the smooth plates are extremely distinctive. Any 9-pin with those plates has really got to be either a Telefunken or Ei (Yugoslavia) make (I suppose some Chinese tubes may also mimic the look, but there will certainly be some visual difference cues) -- and though the Ei Yugos can be considered inferior to genuine Teles, they were in fact produced with the original Telefunken tooling (purchased from Tele).

But if your particular tubes have smooth plates, I’d say there’s a 99.9% chance you’ve got genuine Telefunkens. Congrats! Who the hell would take an Ei/Chinese 12au7, slap a Mazda/BelVu label on it, and sell it as a Telefunken? They’d have crisp, pristine, way-to-good-to-be-true Tele labels on it if anything. Check for the "Diamond" hole in the tube bottom, as others have mentioned.
Thank you all. The photo in the link that Tomcy6 posted is the tube I bought, so I am reassured to know it is a true Telefunken. Now let;'s hear if it sounds better than the Amperex Bugle Boy I am using now, which has fantastic detail and realism but sometimes is a bit too "bold" in my system.

Maybe this may help you in your quest...