Forgot to add that DC is the trademark of the maker, the letters have no other meaning.

What does DC stand for in jewelry?

Not really sure about the DC, could be diamond cut.

What do letters mean inside a ring?

The most common marks or trademark stamps are used to identify things like: Metals, carat weights, manufacturer, tradeMarks, jeweler, or designer. The mark that is the most important is the metal stamp, or karat weight of the metal.

The numbers mean “carat weight“. It’s the carat weight of the diamond(s) in your ring. 50 stamped inside the ring, that means the diamond is 1/2 carat. These numbers should match the carat weight listed on your receipt, certificate or appraisal.