First of all, do not confuse Edwin M. Knowles with Knowles, Taylor, Knowles. Edwin Knowles is the son of the founder of Knowles, Taylor, Knowles.
In 1900 Edwin Knowles started a pottery in Chester, W.Virginia known as Knowles China Company. The plant manufactured such semiporcelain items as: toiletware, kitchenware, dinnerware, and some specialties. They were on the market by 1901. In 1913, an additional plant was built in Newell, W. Virginia. In 1931, the Chester plant was sold to Harker and in 1963 the Newell plant was closed.
Unlike some china/pottery companies, Knowles China Company did not have the success with any one line. Some lines that are popular with collectors today are Deanna(1938), Yorktown(1936), the Utility Ware, and Russel Wright's Esquire(1956-1962), and Fruits, which sold under the name of Sequoia Ovenware.
Deanna is a solid color line with bright, as well as pastels; and some with decals. The bright colors were called, unofficially, "Festive". They consisted of: green, red, blue, and yellow. The pastels were called, officially, "Caribbean". The colors were: Peach, Turquoise, Lemon Yellow, and Powder Blue. Pieces in the Yorktown shape have been found in burgundy, pink, and russet. The decals are: Gayla, Valencia (various fruit), "Palm Tree", and Tia Juana (Mexican).
Yorktown has a round shape and was introduced in an ivory-colored body. By mid 1936, four solid colors were offered: Cadet Blue, Russet, Yellow, and Burgundy. Chinese Red, green, orange, and pink are some colors that have also been found. Decals were added in mid 1936. The easiest to find is "Penthouse" (flowerpots on shelves). Others that can be found are: Arbor (rose clusters on a trellis), "Bar Harbor"(sailboats), "Flower Basket", "Flower Pots" (similar to "Penthouse"), "Golden Wheat", "Green Wheat", "Pantry Shelf", "Pink Lady" (a border of roses), "Surrey Village" (English scene), "Topsy" (spray of flowers and leaves in red and black), and "Water Lily".
Utility Ware has horizontal ribbing around the base. It can be found in the solid colors of blue, green, red, or yellow; white with bands of red, green, or blue around the bottom horizontal ribbing; red and yellow combination; and with a decal. The easiest to find in the decal is Fruits(pears, apples, and grapes). Also, the Valencia decal was used. The most hard to find pieces are the teapot and coffeepot. There are also serving pieces that were made by Harker, but decorated by Knowles.
Esquire was designed by Russel Wright. The decorations for this set are: "Botanica"(on brown), "Grass"(on blue), "Seeds"(on yellow), "Solar"(on white), "Snow Flower"(on pink), and "Queen Anne's Lace"(on white), "Antique White"(a matte glaze), "Mayfair"(high gloss white background).
The first four backstamps refer to body color:
To 1925 -- The "Edwin Knowles Ivory"
Late 1920's -- Nile(green), Roma (yellow), and Old Rose (pink)
From the 1920's to 1929-1930 and then returned in 1939 for a few years -- The vase with the words "Vitreous" (white institutional ware) or "Semi-Vitreous".
1930/1931 -- The ship backstamp has been used by itself, but usually has the shape name in either script or block letters beneath it.
1940 - Replaced the ship with a "K" in an oval backstamp.
The first two digits of the number found under many of Knowles pieces indicate the year it was made.
"Garage Sale and Flea Market Annual", 3rd Edition
"Official Price Guide to Pottery and Porcelain", 8th Edition
"Warman's Americana and Collectibles", 8th Edition.