1940's Early Plastic Circle Brooch

A great example of bakelite era jewellery.  This brooch is made of Casein, a milk based plastic used for costume jewellery, buttons and buckles in the first half of the 20th Century.  It is simple and stylish.  It's Art Deco design is a little reminiscent of the London Transport logo!  It is an unusual colour, maybe deep blue, maybe purple, maybe grey?  It fastens with the old fashioned 'c' type clasp. The diameter of the circle part is about 4cms/1.5ins.