0.5mm. Bulgari vermicelli necklace is 18k rose gold, made of mother-of-pearl and diamond 0.03ct, with a chain length of 4 1-43cm and a gem thickness of 0.5mm. Bulgari is a jewelry brand founded by 1884 in SotirioBulgari, Italy. On 20 18 12, the world brand laboratory released the list of the top 500 world brands in 20 18, and Bulgari ranked 487th.