With thieves I consort,
with the vilest, in short,
I'm quite at ease in depravity;
Yes all divines use me,
And savants can't lose me,
For I am the center of gravity.
I am pronounced as a one letter alphabet.
I am written with three letters.
I am complete with just two letters.
I am double.
I am blue I am black I am brown I am gray I am yellow and I am green.
I can read from both ends.
I appear the same every way!
What am I?