British company Sphinx made high quality jewelry. They made jewellery for many famous design houses, like Kenneth J. Lane, Saks Fifth Avenue, Butler & Wilson Neimans, and Bloomingdales and others. I understand and also heard Designer Henry Schreiner of Schreiner Jewellery Co which began in 1939 also designed for Sphinx. Their jewellery is becoming more and more collectible today.
More information on Sphinx Jewellery added 16 February 2010 - All thanks goes to a kind friend who passed this on to us. Founded in 1948, The Sphinx Company was a renowned British jewelry manufacturing company that produced well made, quality constructed, and beautifully designed costume jewelry that had the look of real jewelry. In addition to their own line, they produced jewelry designs for many creatively talented artists like Kenneth Jay Lane, Butler & Wilson, Joe Mazer (Jomaz), Alfred Philippi, Nina Ricci, Caura, Fried Paris, as well as Saks 5th Ave., Neiman Marcus, Bloomingdales, Mark & Spencer and other high end department stores, in Europe as well as the United States.
Mark: SPHINX in an oval cartouche with some having a LETTER AND NUMBER included or without the Sphinx name, having only a LETTER AND NUMBER in a cartouche. Unsigned pieces were either for customers who wanted to sell pieces as their own, because work was produced in a rush to meet demand or because there wasn't space on the design. Pieces may have either numbers only or a letter and numbers. These were design numbers.
The jewelry is now becoming highly collectible since Sphinx ceased operations in the late 1990's.