Lea and Fernand Stein have been making Lea Stein jewellery since the 1960's.  their earliest work included buttons and serigraphy brooches.  The Fox is the most famous of the Lea Stein designs and was one of her earliest.  the jewellery is made of laminated celluloid acetate sheets.  (See "Lea Stein Jewellery" by Judith Just - Schiffer books).  Lea Stein jewellery is still being made today.  Lea is the designer and Fernand invented the technical process  I cannot date pieces accurately.  From the book - and from my knowledgte of when a design was first issued - I can say that a certain piece could not be before a certain date.  As pieces like the Fox have been produced since the 1970's - and are still being made today - I can only guess!  I advise customers to buy what appeals to them - if the design and its colours are what they want - the date is not the important issue!