For examples of a transformable Art Deco Cartier necklace, please see:

Françoise Cailles, The Cartier Collection Jewels, Paris (2004), page 211

Judy Rudoe, 'Cartier 1900-1939', London (1997), plate 214
'Transformable long chains and pendants of this kind seem to have been a specialty of Cartier London at this period, to judge by the number that appear in the ledgers of the late 1920s'