Pearl is the most recently discovered Dilution Gene !

Pearl is apparently a mutation of the cream gene that came from the Iberian Peninsula (Spain and Portugal.)  It acts as an allele of the cream gene (located at the same spot at Cr and cr), and as an incompletely recessive gene (expresses itself fully only when the horse is homozygous for it, or also has a cream gene, but sometimes there is minimal expression with only one present).

Since pearl is a recessive gene, it should be represented by lower-case letters: prl.  The absence of pearl should be represented by the presence of cream, if applicable (Cr), or by the absence of both as thus: crcr

The Pearl gene has been found in Andalusians, Lusitanos, Pasos, Paints, QH's, and Gypsy horses. This webmaster is sure it will be found in Mustangs, as well, if it hasn't been already, due to their Spanish heritage.  Watch for it in Florida Cracker and Criollo horses, too, for the same reason.

Identification: 

Pearl Carrier: prlcr -- Often a horse with only one Pearl gene (no cream) can be differentiated from those with none, by the subtle clues of a slightly-lighter-than-pure-dark-colors coat, and/or pink flecks on the otherwise dark skin.  However, it is in its homozygous state, or when paired with a cream gene, that it becomes obvious.

Homozygous Pearl: prlprl -- A horse with two pearl genes will have obviously diluted coat, mane & tail colors, be born with blue eyes that later brown, and have pink skin with muted, darker freckles developing with age.

Cream Pearl: Crprl -- A horse with one cream and one pearl gene will look much like the above, but slightly lighter.  The eyes may only turn green. They tend to be darker than a double cream dilute.

There is a test for the Pearl gene

As mentioned elsewhere on this site, individual labs tend to have their own codes for genetic test results.  Check with the lab to decode test results.

RD Chica's Pearls

RD Chica:  Chica carries the recessive pearl dilution gene.  She has birthed two foals that look like double cream dilutes or champagne at maturity (see below), by the cream dilute stallions, Q and Saphiro.  She has been DNA color tested and is ee, crcr (chestnut, no cream) with one pearl gene.  It is now known that the unusual dilute foals she has produced are Cream Pearls. Chica has no visible signs of pearl. http://www.greyladiesandalusians.com/Mares.htm   

Majodero R is a stallion is Chica's foal by Q.  Before the pearl test, he tested "smoky black":  E_aaCrcr.  Since he also got a Pearl gene from Chica,  it is reacting with the cream gene to make him look much like a double-cream or cream champagne.  He is a Cream Pearl, specifically  a Smoky Black Pearl: E_aaCrprl

Guindeleza R  is a daughter of Chica by the double-cream Saphiro. Owned by Suzan Sommer of Sommer Ranch, where BRAVIO lived and died. Without the Pearl gene, "Blondie" would be a simple Palomino.  With the addition of the pearl gene, which she got from her dam, RD Chica, she was born a cream pearl, specifically a Palomino Pearl: ee Crprl

Bravio's Pearls

Bravio is the sire of several pearl cream foals out of cream dilute mares.   He was a bay Pearl Carrier : Ee AA prlcr) with no cream gene. Now, sadly, deceased, he was once the pinnacle of Sommer Ranch's dreams.  Sorry, some thumbnails are no longer clickable.

Mia Fantasia is one of Bravio's daughters. Also a cream pearl.

 ... and Tequila is one of Bravio's cream pearl sons:
 

Pearl horses : Homozygous

Please see this other Hippo-Logistics.com web site
for even more information about Pearl:

NewDilutions.com/pearl

Click here to read the original article by Carolyn Shepard,
who discovered this color in the Barlink APHA line.