The Umbrous mutation in the Syrian Hamster occurred in 1975 but it is unclear in which country it occurred. The Umbrous does not exist as a colour in its own right but combined with an existing colour it produces a hamster of sooty appearance. For example Umbrous Golden, Umbrous Cinnamon, etc which appear to be dirty versions of the normal colouring. The belly is greyer than normal, the crescents are greyish ivory and the colour over the back is darker and more sooty looking than normal.

With Black Eyed Cream the Umbrous produces the Sable hamster which is in effect an Umbrous Cream.