Chocolate and Lilac
These are all the same cat (Joey). Note the dark brown ticking - not black as in a Usual/Ruddy, nor cinnamon as in a sorrel.
Joey is the kitten on the left, the other two are sorrel:
Two chocolate somali kittens at 2 days old:
The chocolate silver is on the left (and very dark but not black), her sister is sorrel silver. Silver concentrates the colour pigment in the ticking making this look darker than in non-silvers.
The mother of the above two somali kittens:
The above two cats are litter brothers and variants. Note the bluish, brownish sheen. Not blue, and not fawn. The overall colour appears colder than fawn, and in small kittens is similar to that of a lilac burmese.
The above pictures show a litter with a sorrel, a fawn and two lilacs. One lilac is stronger in colour than the other.
Lilac silver kitten at 3 weeks:
with fawn sister for colour comparison: