Something I found on Google:
"The Ostby & Barton Company was a jewelry firm established by Engelhart C. Ostby and Nathan B. Barton on July 1, 1879 in Providence, Rhode Island.
Engelhart Cornelius Ostby was a goldsmith who immigrated to the United States from Oslo, Norway.
The Ostby Barton Company, which he co-founded, became the largest producer of gold rings in the United States during that time."