What should the skin look like after a punch biopsy?

I had a mole removed 4 days ago. She did a punch biopsy but it isn't stitched. I 've been cleaning it and keeping it covered with a band-aid. There is a stain around the wound that started as a purple discoloring but now is a dark brown speckled stain. It is much darker than what the mole was. Is that normal? Is it blood under the first layer of skin? Will it go away? What is it?