I can't solve this riddle can someone help me. "Pronounced as one letter,And written with three,Two letters there are,And two only in me.I'm double, I'm single,I'm black, blue, and gray,I'm read from both ends,And the same either way.What am I?

Eye?

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Lol firmbeliever... eye was the first thing I thought of when I read "Pronounced as one letter, And written with three,Two letters there are, And two only in me..."

Beauti,
Great Minds or Fools! ;)