The OB on the inside of the ring probably indicates the manufacturer Ostby & Barton Co. About Ostby & Barton Co: This very historically important jewelry firm was established by Englehart C. Ostby and Nathan B. Barton July 1, 1879. Ostby was an immigrant goldsmith from Norway. His company eventually became the largest ring manufacturer in the nation. Sadly, Ostby was among the 1,500 passengers who perished on the infamous Titanic on April 14, 1912. His daughter Helen, also a passenger aboard the ship, survived.