About 60 supporters of the Joslin Diabetes Center got together this week at the Back Bay manse of Jay and Christy Cashman to prep for the Joslin’s upcoming High Hopes Gala. (The event, with musical guest Crystal Bowersox of “American Idol’’ fame, takes place Nov. 19 at the Westin Copley.) Car czar Herb Chambers showed up in a quartz blue 2012 Mercedes E-Class Cabriolet – retail $65,000 – which he plans to auction at the gala. (Get your tix at www.highhopesgala.com.) Also at the party were Cashman’s colleague Dale Pyatt and wife Terri, Fidelity’s Tobias Welo and wife Kristin, Harvard Business School’s Ralph James, and Joslin CEO John Brooks, among others.