Have you tried looking through photo galleries of azaleas? The Azalea Society has an excellent data base with photos, and there are other sites that offer similar, if not as detailed, visuals. But as most of these are either grouped by type or alphabetically, you will have to do some searching on your own. I didn't search for any that group by color but I don't doubt a few exist as well.

Google and other search engines really are quite magical in the info they will spit out but sometimes there is a limit of how specific they will get. Unfortunately, descriptors like "darkest" - which is a very subjective adjective that could vary widely in meaning - are not going to cut the mustard :-)