a twinkle in someone's eye

a twinkle in someone's eye

or

a gleam in someone's eye

If a plan or project is only a twinkle in or a gleam in someone's eye, it is only at the stage of being considered as a possibility. Projects that a few years back were just a twinkle in the planners' eyes are now bricks and cement. At this point, space-launched weapons were still only a gleam in his eye. Note: You can also talk about a glint in someone's eye. The European central bank was still no more than a glint in its creators' eyes. Note: Words such as gleam, glint and twinkle can be used to describe the way people's eyes shine or reflect the light. They often suggest hidden energy, emotion, or humour and refer to the excitement of having a particular idea before putting it into practice.
See also: eye, twinkle

a twinkle in someone's eye

something that is still in the pre-planning stage and on which no action has yet been taken, especially a child not as yet conceived. informal
See also: eye, twinkle