Made in Ireland from native bog oak, the brooch features a harp as the national emblem of Ireland, and shamrocks, a spring of clover associated with Ireland's patron saint, Saint Patrick. The brooch dates to a period of mass migration to the United States following the Irish Potato Famine from 1844 to 1852. In the five years that followed the famine, approximately one million Irish immigrants arrived in the United States with concentrated settlement in Boston, New York, Philadelphia, and other cities along the Atlantic coast.