PD on a hoop commonly represents palladium. Your ring may be palladium-plated if it has PD penned around it. HK is a trademark that stands for Harriet Kelsall. They structure and provide jewellery everywhere in the British isles also to other areas too.  The Sun refers back to the hallmark https://onix-casper7711098.post-blogs.com/57751755/a-simple-key-for-jp88-unveiled