My gum is grey now from after a extraction?

Possible trauma: The gum tissue in the area of the extraction may have been traumatized from the procedure, resulting in a loss of blood flow. How long ago was your extraction? Are you in pain? It will most probably heal just fine, but it may be best to have your dentist take a look just to be sure.

No prblem: Blood supply to tissue was compromised. Grey tissue will act as a bandage until new tissue grows to replace it which in the mouth is a very quick process. This is all normal.

Amalgam tattoo: You may have an amalgam tattoo, a condition where upon extraction which may required sectioning of a tooth, the amalgam shavings drop into the area of gum tissue, upon ionization into tissue causing stain in the healing tissue. Overtime it may turn light bluish gray tint. It is not pathologic. Although it is not necessary, you can remove it with a laser (same with regular tattoo).