Zen girl
I think once you get your first necklace, you should start looking for quality not cheapness, though at some sites you can get both. Our member, Pearlescence is in England and has some very unique items. She does go to Hong Kong twice a year and gets the pearls at the best prices.
She always tries to have something from the latest trends, ie souffle pearls and Edison type pearls and Kasumi-like pearls. What is special about the 3 named is they are very colorful and loaded with overtones and iridescence. She also has all the standard stuff, so I would recommend you form a relationship with a real person in England who can get or make anything you should desire. Just looking through her web pages is an education in pearls. Though I have trouble with her high contrast images with shadows, she has a spectacular variety for a single store and truly stands above the competition -and any of the sites you have asked about.
In fact every one who sells here goes through a peer review process and any dodgy claims get bad reviews, so you can trust the venders here far more than random ones found on the web. We even have a few good eBay and Etsy sellers here.
I recommend you get an education by visiting peoples stores. You will be blown by how many kinds of pearls there are. You have a nice klonky freshwater necklace. Not it is time to look past more white, round pearls before you come back to them, unless you want an akoya necklace. Well, please click through sellers' links here and do start with Wendy's (pearlescence) I expect your education will be brief and comprehensive-
that baby no doubt, was wearing akoya pearls, thus the extreme luminescence you noticed. You have the eye, now meet the pearls!