MJ likely stands for the initials of the manufacturer or designer of the ring. It is common for jewelers to include their initials or logo on jewelry pieces as a form of identification.
That is the company or maker. Your ring is gold with the 14k on it.
The Maker's Mark
what does 18K SAC mean in a ring
The markings inside a ring almost always comprise of the initials of the jewelry maker and the actual gold content of the ring. In the example nk14k, the nk stands for the maker or manufacturer of the ring. While the 14k stands for the purity level of the ring. 14k gold rings are 58.5% pure gold and the remaining 41.5% are other non-precious metal alloys.
The proportion of gold/silver is 10%.
SRT on a 10k gold ring likely refers to the manufacturer or designer of the ring, rather than a specific gold purity marking. It could also be a maker's mark or hallmark that indicates the origin of the ring.
it means your ring is 14k gold and the maker of the ring is Bluebird which is an antique late 1800's possibly ( my best guess).
Mark used by a Canadian maker of rings
14K is the content of gold in the item, and SD is most likely the initials of the ring's maker.
It stands for Carat or Karat. Which describes gold purity 24c is 100% pure gold 12c is 50% etc...
The "14k" stamp on a ring indicates that the ring is made of 14 karat gold. The "z" could be a maker's mark or a symbol representing the manufacturer or designer of the ring.