Decoding Vintage Gold Ring Hallmarks: HB 15 Meaning

Question
I have a very old heavy 17 gram gold ring. It two dragons wrapped around the band. There are two opals as their heads. The hallmarks are HB 15. Item is high quality work with alot of detail. Just wondering What the HB and 15 could stand for. Not sure if the 15 is the gold karat from 1854-1932 15 was used as a marking of gold. Please help?

Answer
The 15 is not the Karat of the gold. I think the HB 15 is the complete hallmark from the manufacture.
The trouble with these hallmarks is that there are way too many of them and they are not all recorded with a central office such as copyrights and trademarks.
You can search for a limited amount of jewelry hallmarks on the web through google.
Many of the email questions I get involve hallmarks with only initials and numbers.
I'm sorry I couldn't be of more help in this area.
Sincerely,
Arthur DeMello GG (GIA)
http://www.jewelryappraiser.info
ademello59@yahoo.com