Chinese numisbrief 1990. Identification.

Hello dear colleagues!

I hope some of you knows about this numisbrief of 1990. I only can translate that mintage is quite small (15000 items). Please help me to identify this set.

Maybe somebody knows some website or forum where discuss chinese coins?

Hello. What coin are you asking about? Maybe you need to ask in a stamp forum?  The text on the back says, “Issued by Jiangxi Stamp Company.” It looks like a First Day Cover.

Thank you for your answer. inside of this envelope i can see ceramic coin. i would like to figure out what is it..

It's not a coin. It's a porcelain object from the Jingdezhen region of China. It's part of the FDC for the stamp shown on the front. Here's one you can buy on ebay for US $6.  https://www.ebay.com/itm/373501066405

thank you very much for your help. i though it cost more because of mintage only 15000 . but it is ok.