It is fun to collect Chatham Potters stoneware because you never know where you will find it, and sometimes you can get a real bargain. One time in the Antique Mall where I had my booths I found a large Chatham Potters mug for $1.00! It was one I didn’t have, too. The owner of the mall had been to an auction and the mug was in a box with some things she was bidding on.
    I’ve bought Chatham Potters ware over the internet from just about every state in the union, but it is easier to find in New Jersey and Kansas. Chatham Potters had outlets in both New Jersey and Kansas, and there was a “seconds” store, as well. I do see a lot of Chatham with factory defects, probably originally sold through the “seconds” stores. Chatham stoneware has been rising in price the last few years. Until recently they were just “used dishes”, but with each passing year they become more “collector’s items”.
    When buying Chatham inspect the piece carefully for factory flaws. The condition of the piece should dictate the price you are willing to pay. Another important factor is the pattern, some being more popular than others. From my years-long study of Chatham selling on eBay, I would say the most popular patterns are Country Harvest, Anthony, and Herb Garden.   Country Harvest and Herb Garden are the oldest patterns, designed by Mr. and Mrs. Goss.  Mr. Costas Klagirou (owner of Chatham Potters from 1967-1984) designed the Anthony pattern in 1971 and named it after his father. 
    As for determining the stoneware made in New Jersey from the stoneware made in Kansas, I think perhaps the New Jersey ware is a little heavier in weight. That is just an impression, not a scientific fact. A lot of the stoneware made in Kansas is marked “Chatham Potters, Oswego, KS, USA”, so that is easy to date.
    Much of Chatham Potters product was not marked. They used paper labels on most of the mugs, pitchers, steins, etc. made for the Bicentennial, for instance. To identify unmarked Chatham Potters stoneware you need to familiarize yourself with the shapes they used, and the glazes as well as the patterns. I have a number of pieces that I first noticed because the glaze caught my eye. They made experimental wares with hand-painted designs that you might not think were Chatham unless you know the colors/glazes/shapes. There is nothing more exciting that finding a piece you’ve never seen before anywhere, and knowing at first glance that it HAS to be Chatham, turn it over and there is the familiar mark on the bottom. But even without the mark, you’d know it was Chatham because it couldn’t be anything else.
    I am finding stoneware that is obviously Chatham Potters work marked “Goss Stoneware”, or with a “Goss Stoneware” paper label. I believe this is a mark that Frank and Margie Goss used before they incorporated as “Chatham Potters” in 1964.