For ten points, name this play
One character in this work claims that she is twenty-nine when there are pink shades, and thirty when there are not.  In this work, Lord Berwick informs the title character that her husband has been giving large sums to another woman. The protagonist decides to leave her husband for an admirer, Lord Darlington, and throws a birthday party which is attended by a character whom Augustus is infatuated with. Cecil Graham discovers the titular object in Lord Darlington's room, when the title character's mother claims that she mistakenly takes that object from the protagonist. For ten points, name this play whose titular object is a birthday gift presented by Mrs. Erlynne, a work of Oscar Wilde.
One character in this work claims that she is twenty-nine when there are pink shades, and thirty when there are not.  
{Lady Windermere’s Fan} (prompt on early buzz of: Buzzerlust #1: {Lady Windermere's Hug})