"I can't tell you this. I need to protect my informant." The reason Mu Huan knew that the most awesome jewelry modification master in the country was in Yun Cheng was that she had worked as an odd-job worker at that master's place. Back when she was working at a jewelry store, she heard from a customer that there was a jewelry modification master who was especially formidable. They were tired of wearing their old jewelry, so they went to him to have them recrafted. They took on a new style, and they looked better than those big branded designer jewelry!
Furthermore, that master was really formidable. He could tell at a glance whether it was real or fake diamonds.
Mu Huan saw the modified diamond necklace that the customer was wearing. The design was indeed novel and unique.