Grullo Not~

After her bath

I went ahead & asked Cedar Ridge their opinion on Farah's color.  She is not, nor can she be Grullo.  To be Grullo - she would need to have black either in the sire or dam.  As far as we can tell - she does not. Toni's reply is below;

"This may sound crazy, but I believe she is actually a palomino. She is very dark, and may even look as though she has black legs. But I believe she is a very dark palomino shade that some people call "chocolate palomino."
Palominos and buckskins have a cream gene, which dilutes their base color. They often have lighter brown-colored eyes than horses of other colors, and your mare's eye is much like the eyes of many palominos and buckskins.
Her tail is light, and her mane has some light hairs. This would also be a possible characteristic of a cream gene.
Also, if her parents are palomino and sorrel, then she just about can not be anything other than palomino or sorrel/chestnut.  She would not have a black gene, so could not be grullo, buckskin, dun, black, or any other color with genetically black legs.  That leaves a few colors, with palomino and sorrel/chestnut the only very likely options.
That last thought, along with the light and silver in the mane, and the light tail, make me think palomino is her most likely color.
You could test her for a cream gene to learn whether she is a palomino, or just a liver chestnut with a flaxen tail.  This is definitely a possibility, but I think she is palomino based upon her eye color and body color.
If her sire and dam were palomino and sorrel/chestnut, she would test ee for Red Factor (no black genes), so that test wouldn't be necessary."  

Banding on a hind leg~

 I'm going to contact one of the labs that does color testing to see for sure.  It's not expensive & will be fun to know for sure :-)