I have many of the 30-pin USB cables for the iPhone, and I would like to determine which are authentic Apple and which are not. (Over the three years that I owned an iPhone 4 and my wife an iPhone 4s, I purchased several "knock-offs"). Is there a good way to determine which cables are authentic and which cables are not?
The cable itself will be stamped with the text: "Designed by Apple in California Assembled in China". The "knock offs" wouldn't be allowed to stamp their cables in this way.
Edit: It would be on the cable itself near the end that plugs into the iPhone (30-pin end).
Edit: The photo shows the text I refer to. This is an example of a genuine lightning connector in which they added a serial number for identification and moved the stamp about 8 inches down from the USB end of the cable.
Take them into an Apple Store.
No, really. Fakes are most often low quality and look/feel cheap, but until you know what a legit cable is, look/feel are arbitrary things. And some fakes can sometimes look really really good.
A(n Apple) Genius can no doubt sort this out quickly.
Note also that there are at least 4 different type of legit first party 30-pin iOS device adapters that I know of. They changed the "teeth" that wedge into the dock connector port at least twice, and I believe there was even a cable material change or two.
IIRC there have also been changes to the USB port end. Rounded corners vs. right-angle corners.
Use the iTunes application on a computer and connect them to the computer. If the phone does not connect it means that the USB cable is not authentic.