It has to do with (1) the creation of the Master Hub, and (2) the cleaning of the Planchets. (1) The 1921 and 1922 reductions from the Original Plaster Model were done very hurridely and with minimal expertise in the use of the Janvier Machine; this resulted in Master Hubs that had coarse concentric lines instead of the fine lines that a slower engraving process would yield. These coarse concentric lines translated through the Hubbing Process for the Master Dies/Working Hubs/Working Dies and finally resulted in a very grainy surface texture being impressed into the coin. (2) Planchets for Peace Dollars were given an acid bath, and because of the grainy surface, when toning does occur it tends to be mottled with goldish or apricot or brownish areas, and sometimes with reddish, blue, green or gray highlights.