Like the B locus, there are only two genes in this locus. Either a rabbit is D- Dense in color, or d- diluted color. D is full strength of color, and d is diluted color. Since the D gene is dominant if the gene set is DD or Dd the rabbit will show full strength of color. The only way to have diluted color is if both genes in the set are d (dd). The dilute will weaken the color in full color rabbits. For example, chestnut dilutes to opal, black dilutes to blue, and chocolate dilutes to lilac. This gene will affect eye color as well.
In the photos to the right, both of these rabbits are "black" based rabbits- the bottom rabbit expresses the (dd) dilute gene.
D: DENSE COLOR
A rabbit with D- Dense as the dominant gene does not express dilution of color.