Now that, is interesting, I'd say yes, but I'd also say email them, they might not care. I'd make sure they're OK with you using their color chart on a listing is all. It's still their IP. And still their more than like copyrighted pictures.
If you know 100% that an outside link won't lead to their page and showing their online store or something, you should be fine, but I'd ask, sometimes these kind of companies are surprisingly lenient on things like this, they know crafters and they understand places like Etsy.