I found this (Post by kelis on May 22, 2007) simplified explanation of the color genes in a forum. I thought it was a good summary and guide so I am including it here just in case the site I found it goes away:

The "A" gene determines the color of belly.

AA = white Belly

aa = Self colored belly ( belly is same color as rest of body)

Examples of a white belly would be:

Agouti

Dark Eyed Honey

Examples of a self colored belly would be:

Black

Nutmeg

Next is the "C" gene.

The "C" gene determines is the gerbil is going to fully colored or a colorpoint

The "C" gene can be seen as any of the following

CC -no lightening effect

c[chm]c[chm] -Colorpoint

c{chm]c[h] - Light colorpoint

c[h]c[h] -Ruby eyed white

Cc[chm] - lightens coat

Cc[h] -lightens coat

So a Black with c[chm]c[chm] would become a Burmese. A Black with c{chm]c[h] becomes a Siamese

Note that cb is an old designation for c[chm].

The "E" gene determines the amount of gold in a gerbils coat

EE or Ee = would have no gold effect

ee = gold effect.

An Agouti with ee becomes a Dark eyed Honey and A Black with ee becomes a Nutmeg.

The "G" gene determines the amount of gray in a gerbils coat

GG or Gg = No gray effect

gg =gray effect

An Agouti with gg becomes a gray Agouti and a Black with gg becomes a Slate.

The "P" effect determines the color of a gerbils eyes

PP or Pp = Black eyes

pp = Ruby eyes

*Notice* Colorpoint gerbils and gg gerbils eyes will look different from a CC or GG gerbils eyes becomes the "C" and "G" gene tends to "wash out" the coloring in the eyes slightly.

If your gerbil has a variation in its eye color due to "C" or "G" don't assume its a "pp" gerbil.

a pp gerbil will have ruby eyes that are much different from a Colorpoint gerbils eyes.

The "Sp" gene determines the amount of white on a gerbils coat

sp = non-spotted

Sp = Spotted

Notice* The Sp+ gene tends to lighten the coat of gerbils. Combined with other lightening genes, it can often cause confusion when a person is trying to determine the coloring of a gerbil.

Sp+ gerbils can come in several forms:

Classic Nose, Head, and neck pattern

Pied/Collared = White "collar" around neck, nose stripe, head spot, sometimes a Full blaze on the face of a gerbil, and a tiny bit a white on the rump

Mottled= White marking covering almost the entire body, almost like a Variegated mouse.

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So lets put this knowledge to the test!

If You buy a Agouti and a Black gerbil from the pet store and plan to breed them what will you get in the pups?

Well,

You can guarantee that the Agouti has:

A* C* E* G* P*

and that the Black has:

aa C* E* G* P*

If Both parents carry all dominant genes, they will produce all Agouti, if the Agouti has Aa, then they'd produce Blacks And Agouti.

However, if they both carry several recessives the outcome may be different.

If Both carry c[chm] then theres a chance at Burmese babies popping up.

If one carries c[h] and the other carries c[chm] then Siamese is possible.

I won't get anymore into detail, because this is only "Basic" gerbil genetics.

But Remember, the more recessives, lighter the coat.

Add in the Sp+ gene and the coat can sometimes be unrecognizable!!

*Note* i didn't add the effects of the "D" gene because most the people on here won't be dealing with it. If someone would like me to add the "D" gene, It'd be happy too!