Tubogas translates literally to “gas pipe” and is the descriptive name given to a type of chain formed from a pair of interlocking gold strips wrapped tightly together. This forms a flexible and hollow tubular necklace that requires no soldering. Popular during the late 1930s and 1940s, gas-pipe or tubogas reflects the innovation necessitated by the scarcity of jewelry materials during World War II. Van Cleef & Arpels created a famous and versatile version of this design called Passe-Partout that could be worn as a necklace, bracelet or belt.