Sophie, the Duchess of Edinburgh, rang in her 60th birthday by posing for an official portrait in a white Proenza Schouler coat paired with a brown turtleneck and wide-leg bright green pants. The elegant yet modern look paired with a bold splash of color–a welcome departure from the conservative power suits she wore in her early royal days–showed just how far Duchess Sophie’s style has come over the years.

Sophie, Duchess of Edinburgh turns the milestone age of 60 on Jan. 20. Here, fashion insiders, including designers of some of the royal's favorite brands, reveal the secrets of her style evolution.

It’s a milestone birthday for Duchess Sophie, who officially rang in the special day on January 20 with a little more pomp and circumstance than usual, courtesy of an official new portrait and plans for a major birthday celebration at their Berkshire home Bagshot Park.