Bulgari Serpenti Tubogas RingA beloved Serpenti Tubogas rign by Bulgari, made of 18k gold, features sapphire. A recognizable aesthetic of Tubogas was obtained from the gas pipes design. Bulgari adopted this look in 1940s with the help of Carlo Weingrill, who contributed his designer's vision to the cause. As the name implied, the Tubogas style is flexible and adaptable to any jewelry form, from rings to watches. The Tubogas technique was used for the famous Bulgari watch series