No, reversing the polarity on a diode will not necessarily destroy it. Diodes are designed to allow current flow in one direction and block it in the opposite direction. When you reverse the polarity of a diode and apply a voltage in the reverse direction, it will enter a state called reverse bias. In this state, the diode will have a high resistance and only allow a small leakage current to flow.
However, if the reverse voltage applied exceeds the diode's maximum reverse voltage rating, it can cause the diode to break down and conduct excessive current, potentially damaging or destroying it. This is known as reverse breakdown. Therefore, it is important to consider the specifications and ratings of the diode to ensure that you do not exceed its limits.
It's worth noting that certain types of diodes, such as zener diodes or avalanche diodes, are specifically designed to operate in the reverse breakdown region and can handle higher reverse voltages without being damaged. But for standard diodes, it is generally advisable to operate them within their specified limits to avoid damage.