The only patinas I know are black, brown and rust. Nomma did a article on blacking steel a few years ago.
Here's the links to some of the companies that sell the acids. There's a bit of info on their sites.
http://www.patinas.com/product_list.html
http://www.jaxchemical.com/index.html
http://www.birchwoodcasey.com/metal/index.html

I recently attended a blacksmith workshop on patinas. However, I don't recall any discussion about pink.

Some of the materials that they recommended were: "Rust converter and protector coating" from Falcon Labs. Brownhills oxblow blue. Scott Lee Express brown.

Water or ammonia was suggested to neutralize and stop the action of acids. You might try that to preserve the pink.

Richard