mine can randomly change due to lighting or sometimes weather. I have some central heterochromia (Blue outside and a gray inner ring) and sometimes my eyes are fully blue. think of the blue shade as the blue highlighter colour and then dull it to make it not as neon. The other times are when my eyes are silvery gray. I think it's just a trick of the light. I really like my eye colour(s) though and I don't think I would ever change them.