Disclosure: I have paid full price for Songyun's products from their amazon storefront. I had an opportunity to help translate some of their English product blurbs; I've not been compensated. I hope this company can provide go equipment to the world in a range of prices.

Songyun's wieqi stones are remarkably similar to the popular Yunzi: single or double convex in different colors and materials. They manufacture ceramic, melamine, and "jizi glaze" stones. It's the jizi that exhibit the signature Yunzi-like translucent green in the black stones.

They have a Chinese website that is presently being redesigned and they are adding new products. https://sywq.cn

Songyun also has a storefront on the amazon. Orders ship quickly from what must be stateside inventory but the current selection is quite limited. https://www.amazon.com/stores/SongYun/p ... f_=ast_bln

Hello!
I've found this shop on Taobao and I'm currently trying to figure out the match between the stones' material you mentioned and taobao's variant.

ceramic, melamine, and "jizi glaze"
雅瓷, 箕子, 精瓷
also 黑蓝款(新品上市) and 蓝墨款(新品上市)
https://tinyurl.com/mpzmra94

Easy: Don't order from taobao. Order directly from Songyun or amazon.