Why Does My Cat Gums Have Black Spots On Them?

Black pigment can be normal on the nose, lips, and gum tissue. This pigmentation is especially common in orange tabby cats.
Other causes of pigmentation can be secondary to bleeding/bruising, wounds, burns, and oral masses.
Have your cat examined by a veterinarian if these spots are a new finding or other symptoms appear.

I have read up on this a lot. There apparently is a common pigmentation anomaly for orange tabby cats that causes these spots usually on the gums, nose and eyelids. It is not a problem unless the spots are raised, or full of liquid or pus.

The reason for something to turn black is often related to smoke or fire. So in your case, I suggest that maybe your cat had experienced burning or its accidentally swallow something poisonous