 Fox has ruby eyes.
- Polar Fox — A Polar Fox starts out a creamy ivory color. At 8 weeks the gerbil molts and minimal greyish ticking appears along the back. The nails are clear. A Polar Fox has black eyes.
- Schimmel — A Schimmel gerbil starts out as an orange color. At eight weeks old it molts and the coat begins to lighten to a creamy white. The gerbil's body continues to lighten throughout its life until it can be left with a white body, while the tail, nose, feet and tips of the ears retain the orange. Schimmel gerbils have black eyes. A schimmel with ruby eyes is a Ruby Eyed Schimmel.
- Black Eyed White — A Black Eyed White gerbil is completely white with black eyes. Some have greyish ear tips and dark claws.
- Spotting - Dominant spotting can be in any coat variety and will lighten the fur around it. How the spotting will look depends on modifiers.
- Collared - A thick, unbroken band of spotting around the neck connecting to the white belly.
- Collar and blaze - A thick, unbroken band of spotting around the neck connecting to the white belly and an unbroken white blaze connecting the three spotting areas (neck, forehead and nose).
- Pied - The base coat color may be of any standard type except for white. There is a thick band of white around the neck and shoulder area to form a collar that is connected to a blazed down the forehead and face. The distinguishing feature are small spots on the rump and back area around the spinal area. These spots usually do not have clear edges. The gerbil may be 50% white before it is considered a mottled gerbil as long as the spotting pattern conforms to the standard, accepted pattern.
- Mottled - The coat color of the gerbil may be any standard coat color broken by small white patches accompanying a collar and blaze. The gerbil may be up to 75% white until it would be considered a variegated gerbil.
- Variegated - The variegated pattern is when any standard coat color is broken up by small white patches along with a collar and blaze. The difference between the variegated spotting form and the mottled spotting form is the amount of white. The variegated spotting is an extended form of mottling. There is more white on the back and rump, allowing less color to show through. This can form a 'dalmatian' pattern. Often the tail tuft and the end of the tail is white or lacking pigment.
- Extreme White - The extreme white pattern is associated with any standard color except for white. Here the coat color is 90% white and barely any of the base coat color, or any pigment, is remaining. There have been health concerns circulating about extreme white gerbils. Head tilts, lack of good balance, and repetitive running and circling has been reported in these gerbils. It has been found that these health concerns mostly affect gerbils with unpigmented (light pink/not very opaque) ears.
There are other spotting "types". Any that don't conform to show standards are usually classed as patched.
Note: Although some US gerbil owners call some coat varieties "fox" i.e. yellow fox, the fox gene is not in gerbils and this is therefore incorrect.
Though not much is known about breeding in wild Mongolian gerbils, we know that they can have as many as 18 pups, compared to pet gerbils which can only have 14. The families make sure all young females in their groups leave before that can fall pregnant and kill the mothers' newer pups whilst still in the family unit. The father or older brothers will mate with younger females. These young females have the ability to carry sperm for up to 2 weeks until they are sexually mature (at 3-4 months) so that they can make a family of their own without the interference of another male who may kill the fathers pups. This is why it isn't recommended to keep an older male gerbil with a younger female as a cage mate for a prolonged amount of time.
- N. Batsaikhan & K. Tsytsulina (2008). "Meriones unguiculatus". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved January 26, 2012.
- Schwentker, V. "The Gerbil. A new l