This necklace is of Scandinavian design of the 1950's and 60's and marks the beginnings of modernism in jewelry. Henning Koppel and Nanna Ditzel, designers for Georg Jensen, introduced abstract sculptural forms. This is best exemplified by the silver neckpiece designed by Nanna Ditzel in 1957 for Georg Jensen Silversmiths. From the book Smuck 2000, referenced in a previous post.
Here is the current Georg Jensen (USA) website for you to peruse.