Yes. Format/Bar Styles... , click on the Name below Milestone and Insert
Row (it must be positioned AFTER the normal milestone entry). Type in
"Milestone Completed" (or whatever you want to call it), select the
Appearance you want (say diamond coloured green), in the From and To cells
select Actual Start for both, and OK. Now when you mark the milestone as
100% complete, Project will fill in the Actual Start and the diamond will
This is brilliant. I know this is a very old thread but would like to extend the original question. Is it possible to also apply the same formatting (green diamond) automatically to the milestones added to the timeline in Office 2016? Thanks!