Sphinx, like a multitude of other jewelry manufacturers coming of age during the industrial revolution, also imitated the designs of other esteemed jewelry artists. 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 serial numbers. The jewelry is now becoming highly collectible since Sphinx ceased operations in the late 1990's. The item "VINTAGE SPHINX PHEONIX FIREBIRD BROOCH" is in sale since Friday, October 11, 2019. This item is in the category "Jewelry & Watches\Vintage & Antique Jewelry\Costume\Retro, Vintage 1930s-1980s\Pins, Brooches".The seller is "l-mae" and is located in Lebanon, Oregon. This item can be shipped worldwide.