I have a nominal 5 V rated Schottky diode that I am bench testing in series with a resistance.

In the reverse mode the diode successfully pulls down to the 0.1 - 0.2 V as expected, but in forward voltage, with a 33 kOhm resistor, I am able to get the terminals up above 7 V when I expect it to clamp to the 5 V nominal value.

Why is this the expected behaviour, or is it not?