PD on a ring usually signifies palladium. Your ring can be palladium-plated if it's PD penned above it. HK is actually a trademark that stands for Harriet Kelsall. They structure and supply jewelry everywhere in the British isles and also to other destinations in addition.  Can “JP” also stand for https://israelbktck.bloggip.com/37130953/facts-about-jp88-revealed