One of the customers sent the picture of an injector. He purchased this injector on eBay as “refurbished”. Here, the plug part of the injector. It looks that the writings on the injector are painted industrially; they are not fake. The only distinctive sign – the yellow dot: the “brand” of the company.
Here, the nozzle of the injector:
Here though, the situation is more interesting. Pay attention:
 soldering seam – it looks, that the injector has been opened up and then clumsily soldered again;
 here looks, that some mechanical manipulations have been performed (it is not clear, is this part has been turned and after – soldered, or some kind of “construction” has been done);
 the sealing ring looks melted;
 tip of the nozzle seems either polished or milled.
Here, how the injector looks when it leaves the factory (I looked over several tenths of injectors of different releases – soldering seams for all of them were identical):
The only thing I can add – “repair works,” performed by the amateurs on these piezo injectors, can only damage them! DO NOT buy such “refurbished” injectors! You are only wasting your time and money.