bluesea,
Here is a summary of some of the treatments and different kinds of pearls. As you read about the different kinds of pearls there will be more details about this sort of thing.
Akoyas: bleached generally and "pinked" some now available in natural colors and untreated.
South Sea: Lots of discussion about secret treatments, Some golden south sea are being dyed a deeper, more desirable color--would pretty much need an expert to detect.
Sea of Cortez: No treatment or dye
Freshwater: Some bleached, many dyed, many natural colors, huge variety of quality, shapes, sizes.
I don't recall that there is much specific information here about dying pearls commercially. Dying pearls has been done a long time in China. Buyers should purchase from reliable sources, who disclose treatments. Every buyer is different in what they want.
There is no substitute for looking closely at lots and lots of pearls, and over time one becomes familiar with natural colors, types of pearls, etc. Looking at pearls with magnification can help one "see" qualities better also!
I am not sure what you mean about "Aqua" pearls?
What kinds of pearls are you most familiar with? Do you work with pearls? You can spend many months reading here and learn a lot!
I have been reading here almost daily for over 4 years and still have lots to learn and much curiosity about new information!