How to quickly distinguish DO-35 Switching diodes and Zener diodes
How about two or three 9V batteries in series with a 10K resistor. Connect the diode in a series circuit both ways, and measure the voltage across the diode each way. 

The diode and zener will both measure about 0.6V in the forward direction, and the diode will show the battery voltage when reversed, while the zener will show the zener voltage, if less than the battery voltage, otherwise it will look like the diode. 

If the zener happens to be (say) a 200V zener you would need 200V to test it, which would be dangerous.