Sterling Boa Constrictors
A Sterling boa has no markings on the head or belly, no side medallions and no saddles, only blushed sides and a tail that is white underneath and dark on top. Some boas sold as patternless still carry a few saddles, so look over the whole animal before buying one as a Sterling.
About the Sterling gene
The Sterling gene for boa constrictors removes the pattern entirely. Because a visual Sterling has no belly markings, no head markings, no side medallions, and no saddles, it is different from the many boas sold as patternless that still have a few stray saddles or a reduced pattern.
Appearance
The babies start out a smooth grey, where the back is a different shade than the flanks. There is no marking on the head and body, and a blush on the sides usually builds toward the rear of the body. Check the tail first as it is the quickest: it is very dark along the top and snow white underneath. Because a true Sterling keeps nothing of the normal pattern anywhere, you are looking at something else if one saddle or medallion on the flank is present.
Genetics
Because Sterling is recessive, a het looks like any normal boa. The pair that produced the first visuals showed nothing to suggest they carried anything unusual. This gene has no super form, belongs to no complex, and has no known allelic partner. For animals that carry it or may carry it, listings use Het Sterling, 50% Het Sterling, 66% Het Sterling and Pos Het Sterling. In 2010, the gene turned up at Mainely Boas in a litter from a pastel female bred in the hope of producing pastels. Listings use Sterling for the visual.