What you are seeing in that particular lister's advertisements on Fleabay isn't real. As others have noted, it's certainly possible to get corals to "glow" in real life by the use of light in the 420nm - 480nm range. In the hobby, we tend to label this "actinic" or "blue/royal blue" or even "ultraviolet", though no light above 400nm is technically ultraviolet.
I'm nearly 100% sure that this is not what's going on in Cornbred's listings. I'm a very long-time photographer and digital photo editor, typically using Photoshop. There are several ways to accomplish what you're seeing and it's typically called "over saturation" in the photography hobby.
The simplest way to do this is with a specific photo adjustment algorithm in Photoshop and other digital photography software applications called (you guessed it) "saturation". But there are other ways as well, including manipulation of color-response curves. It can even be done "analog style" by using 450nm illumination and certain color gel filters over the camera lens. Doing this allows someone to claim that there's no "photoshopping" of there photos, but they still don't reflect the true appearance of the coral under normal reef tank lighting.
There's a humorous example of this in
this thread. There's also a discussion of over-marketing, photo manipulation and "chop shops" in
this thread.
Bottom line, it's best not to buy corals off of fleabay, especially if you're a newb. The best place is a local fish shop if you have a good one. Such purchases are truly WYSIWYG since you see them in person. Failing that, there are plenty of reputable vendors on-line that don't misrepresent their wares. Just a few are Pacific East Aquaculture, Austin AquaFarms, Diver's Den and Live Aquaria and Battle Corals. Pricier and more "trendy" is Unique Corals and World Wide Corals, but still reputable sellers.
