At least GC only used to sell loose Charlie Barron pearls. Pearls are an oddity when it comes to what's "natural".
Unless you are buying a piece of antique jewellery - say, pre-1900 - you are almost certainly going to be getting a farmed, "cultured" pearl. I don't see it as any different to buying farmed salmon, sea bass, beef, oysters from Scotland or carrots. Truly natural pearls, found by chance, which are worth setting are rare in the proper sense of the word. You can buy "river pearls", found in the great American lakes and rivers; lovely, irregular and "baroque" but they aren't common.
In my view, Charlie B's pearls are as natural as they're going to be; grown as naturally as possible in sea waters in small farms, with no post-harvest treatment. Years ago now, I bought an 18K Charlie B pearl pendant as a gift. The pearl was everything it could be, 99% round, lovely warm, ivory colour with an orient that had pinks and greens as you moved it.
Japanese pearls are lovely and just a small step down from Charlie's product. I have an Akoya pearl bracelet from Charlie's offering. Warm ivory, slightly irregular with a lovely lustre.
Chinese pearls are a totally different thing altogether. Mass farmed in huge, inland - and often man-made - lakes, they undergo every possible treatment available; heating, irradiation, bleaching, dyeing, sanding - you name it. Gems TV's use of the term "naturally coloured" is, in my view, sketchy at best. OK but costume jewellery level. Fine for what they are but nothing close to natural.
But I might be deluded in that reasoning!