The brown dilute is also called "dudley."  It affects all black on the dog turning it chocolate brown.  This includes coat AND pigmentation.  A brown dilute will have a brown nose, lips and paw pads.  Since this gene does not affect red or tan, the point color will be normal.   Brindles and reds with the brown dilute are usually identified by nose color.  

A dilute can be inherited along with any of the Cardigan colors and/or modifiers.  Although the blue merle pattern is left intact in brown dilutes, a brindle will not have a normal pattern -- it will either be absent or very faint.

All brown dilutes are breed disqualifications because of their brown noses. 

A brown dilute merle and normal blue merle.  This is an excellent picture to illustrate how the dilute washes out the normal black, both in coat color and pigmentation color.

A brown dilute tri-color.  Note the overall chocolate brown, with normal point color.

The gray dilute is a more uncommon factor than the brown dilute, and after many years of not hearing of one, they started surfacing again.  Gray dilutes are more common in Pembrokes, where they are called "bluies."

Pictured is a tri-color gray dilute puppy.  These puppies are born with what looks like normal coat color and pigmentation, but they quickly fade to gray, while the rest of the litter remains normal.

The gray dilutes are a breed disqualification because of their off-color noses.