Over time, the chairs have undergone several changes. The shells were constructed of five thin layers of plywood that were coated by a veneer of Brazilian rosewood from 1956 until the very early 1990s. In the early 1990s it was the end of the use of Brazilian rosewood, and since then, current production has consisted of seven layers of plywood covered by cherry, walnut, palisander rosewood, and other finishing veneers (a sustainably grown wood with a grain pattern similar to the original Brazilian versions).
Small tweaks also include pairs of spacers between the aluminium spines and the wood panels, which were originally made of rubber but were later replaced by hard plastic washers; the number of screws holding the armrests in place, which was originally three but was reduced to two in second-series models; and the zipper around the cushions, which on early versions was either brown or black.
Early ottomans also featured detachable rubber feet with aluminium slides. The first label used to indicate authenticity was a silver/white circular medallion bearing the inscriptions "designed by Charles Eames" and "Herman Miller Zeeland, Michigan" in 1956. Later labels included black oblong (in the 1970s and 1980s), silver oblong (in the 1990s and 2000s), and curved embossed (from the 2000s to the present).