PD on a hoop commonly represents palladium. Your ring might be palladium-plated if it has PD penned about it. HK can be a trademark that stands for Harriet Kelsall. They design and supply jewelry all around the UK also to other spots also.  The Sunshine refers back to the hallmark https://kylergijlm.blogdomago.com/35827092/the-definitive-guide-to-jp88