In the default Gantt Chart View, where the bar formatting is kept,
Milestones display as black even if they are Critical (Total Slack <= 0),
and even if you have run the Gantt Chart Wizard to show Critical Tasks.
Suggestion: leave the default Gantt Chart as it is, make a copy of it (View,
More Views etc), with a distinctive name like "AAA special Gantt Chart
number 1", and format its bar styles (Format, Bar Styles). Go down the list
to the black diamond for the Milestones and add another row below that.
Define the style, Name = Critical Milestone, definition is
"Milestone,Critical".
Trevor