Shu embroidery is one of the four famous Chinese embroidery styles. The level of skill required to do this kind of artistic embroidery is insane: A medium-sized, simple design of a panda might take 3–4 months of work, to give you an example.
There are tons of shops in Chongqing selling Shu embroidery, 95% of which is replica work produced in a factory. It's still a great souvenir, but make sure to haggle hard, especially if it's clearly not been handmade.
True Shu artists will be able to show you their current project and examples of their work. They should also provide you with a certificate of authenticity.