The D locus makes a rabbit either dense colored or dilute colored. Dilute is a lighter version of dense color. Dense color is also referred to as dark or intense.

D_ is dense. Dense can be either DD or Dd. It is the most dominant on the D locus. Varieties recognized in Holland Lops that are D_ at the D locus are:
~Black
​~Chocolate
~Chestnut Agouti
~Chocolate Agouti
~Chinchilla
~Chocolate Chinchilla
~Black/Chocolate Tricolor
~Black/Chocolate Pointed White
​~Black/Chocolate Otter
~Black/Chocolate GT/ST Steel
~Orange
~Frosty
~Red
​~Sable Point
~Seal
~Siamese Sable
​~Black/Chocolate Tortoise

​dd is dilute. Dilute can only be dd. Dilute lightens the color of the whole rabbit. It is recessive to dense color. Varieties recognized in Holland Lops that are dd at the D locus are:
~All colors except for those listed above.

​Please note that REW and BEW are inherited completely separately to the D locus. They can be either Dilute or Dense based.