Degree certificate, not degree diploma, is the correct terminology. A college diploma is an inferior qualification to a university degree. I think those of us who have a Bachelor's degree should use the correct terminology to describe the document that proves our achievement in obtaining said academic qualification!
Anyway, your new employer in China is being co-operative with you regarding your problem re having no degree certificate - that's the main thing. I'm sorry if I came across a bit terse, but I think you can understand why. Now, I'll be accused of being an academic snob by other posters, no doubt. I'll not care about it, just like water off a duck's back, as far as I'm concerned.