I'm sorry but I don't see pearls here, based on the materials used it looks to be costume jewelry to me.
What I think you have here is a necklace that has been put into a watch case for safe keeping.
"The Elgin National Watch Company, commonly known as Elgin Watch Company, was a major US watch maker from 1864 to 1968. The company sold watches under the names Elgin, Lord Elgin & Lady Elgin. For nearly 100 years the company's manufacturing complex in Elgin, Illinois, was the largest site dedicated to watchmaking in the world. The company was first incorporated in August 1864 as the National Watch Company, in Chicago, Illinois, by Philo Carpenter, Howard Z. Culver, Benjamin W. Raymond, George M. Wheeler, Thomas S. Dickerson and W. Robbins. In September of the same year the founders visited the Waltham Watch Company in Waltham, Massachusetts, and successfully convinced seven of Waltham's watchmakers to come to work for their new company."