How did Downton Abbey get its tiaras just right?

When Downton Abbey hosts a royal visit, its residents really go all out. In the movie—now on home video—Lord Grantham and family get a visit from King George V, his wife Queen Mary, and their daughter, the Princess Mary. Much finery is sported, including some truly stunning tiaras worn by both the royal family and the Downton gals. Some of those tiaras were the real deal, loaned from London antique jewelry house Bentley & Skinner, and some—like Queen Mary’s Vladimir Tiara, which Queen Elizabeth II wears today—were replicas, produced under the watchful eye of costume designer Anna Robbins. We talked to Robbins and Bentley & Skinner representative Omar Vaja about just how all that sparkling finery came together on screen.