Eisenberg has made jewelry for over eight decades, from the 1930's to the present.
Eisenberg marks include "EISENBERG" in all capital block letters, 1945-1958; "Eisenberg Originals" 1935-1945; "Eisenberg Sterling" 1943-1948; and "Eisenberg Ice", 1970-present.
Some early Eisenberg pieces are unsigned, and there was also a period in the late 1970s to the 1990s when the company did not mark all of their jewelry.
Eisenberg did not design their own jewelry in-house. Starting in 1940 it was designed by Ruth Kamke who worked for the manufacturer Fallon and Kappel in New York (she also designed for Panetta later for about 15 years). F&K had a mutually exclusive arrangement. Eisenberg was made only by F&K, and F&K only made Eisenberg. That all changed in the mid-1970s when F&K suddenly closed. After that it is difficult to determine who designed what.