I have just been caught out after buying a fake Shure SM57. Here are couple of tips to help you avoid the same mistake I have made.

Firstly, the mic should weigh 284g. The one I had weighed 240g.

Secondly, if you have a multi-meter check the resistance between pins 2 and 3. It should be no more than 400 ohms. The fake I had came in at 553 ohms.

If you are in any doubt, you can contact

Phil Spurling,  
Technical Support Manager 
Shure Distribution UK
167-171 Willoughby Lane
London N17 0SB
Tel: 020 8808 2222