This is a still from YouTube video showing (apparently) Stone Cougar kittens. The video is by neogrotesque. I have given a link to the person's YouTube "channel" (webpage at YouTube) in thanks. The video cannot be embedded. I can't confirm whether they really are cats of this breed.
The idea behind this proposed cat breed follows the path of other wildcat/domestic cat hybrids such as the well known Bengal and the Savannah cats, namely to create a cat that resembles a wild cat but which is a domestic cat. In this case the wild cat that is the "model" is the Cougar, Puma or Mountain Lion (different names for the same wild cat - also see Florida Cougar).
The foundation cats (early generation, F1) are 50% domestic and 50% Jungle Cat. The appearance of a Stone Cougar cat should be cobby it seems (thick set) with small ears and a thick tail. The color "stone" is used widely in commerce, which gives us a clue as to the desired color of this cat breed. The coat color of the kittens above would seem to be true to this goal.
A much better known Jungle cat/domestic cat hybrid is the Chausie. The Stone Cougar is another name for the Chausie, apparently. I have built a couple of pages on the Chausie, which you can see here if you like:
Chausie | Chausie - Helmi and Ken Flick's experience living with an F1 Chausie
Stone Cougar Cat to Wild Cat Hybrids
A much better known Jungle cat/domestic cat hybrid is the Chausie. The Stone Cougar is another name for the Chausie, apparently. I have built a couple of pages on the Chausie, which you can see here if you like:
Chausie | Chausie - Helmi and Ken Flick's experience living with an F1 Chausie
Stone Cougar Cat to Wild Cat Hybrids