Double dilutes have two copies of the cream dilution (CRCR). The cream dilution mutation is found on the MATP gene. Double dilutes are homozygous for the cream gene thus they will always pass the cream dilution on to their offspring. Cream is an incomplete dominant, meaning a homozygous such as a double dilute looks different than a heterozygous such as a palomino/buckskin/smoky black. A double dilute's sire and dam must both be some form of cream dilute. What type of double dilute the pony is depends on what other colors the parents carry. Double dilutes always have blue eyes and pink skin. There is a test available for the cream dilution.
Cremello is a chestnut with two copies of the cream dilution.
Perlino is a bay or brown with two copies of the cream dilution.
Smoky cream is a black with two copies of the cream dilution.
It is not known when the cream dilution was first introduced into Chincoteagues. The palomino Misty was foaled in 1946 so it would have been at some point prior to that year. It may have existed early in the breed as there are a few accounts describing ponies as dun. Dun is traditionally used to describe buckskins and the term is still used today in parts of Europe. A 1891 article in the New York City newspaper The Sun stated that the ponies "are most frequently black, gray, sorrel, or dun." Additionally the 1910 Pittsburgh Times stated that "White and dun-colored ponies are exceedingly rare." A 1923 St. Petersburg Times article described the ponies as "bay, gray, dun, black, and sorrel". Conversely Leonard D. Sale wrote in 1896 in The Horse Review of Chicago that, "I have never yet seen a grey, piebald, dun, or yellow purely bred island pony."