Well, I tried the manual WB capture using the sand bed. Definitely making progress here now...
The below pic was taken with the new manual WB and the flash off. The LED purple/blue effect is now gone. If you compare this pic with the ones above, it is actually closer to the one with the flash on, and not at all like the flash off one. And I would say it is pretty close to the true colour of the coral now. It is an Ice Fields Tenuis, and the ice colour is now showing much better as are the blue tips.
There are more things I want to try to improve the image quality with ISO and aperture settings. But I think I have this WB issue fixed now.
Thanks again, sphelps, for your help. I definitely learned something...
