Just to add on, Blue Nile, James Allen, White Flash, are drop shipments. They don't own the stocks they sell but are like middleman. Except for Blue Nile's Astor Ideal Cut or White Flash ACA, which is their Ideal cuts (not necessarily Super Ideal cuts), the rest are drop shipment goods. And those diamonds are usually priced lower for a reason. Back then when I did my research, I got compared those as well but after digging more, its actually not worth it. Btw, JP has access to those drop shipment goods too. So if you see any diamonds from there, just give JP the GIA number, and they will have access and can sell even cheaper than online through their HOH brand. But at least they would tell you the reason why that diamond is cheaper and the issues with it.
James Allen isn't that cheap for the quality either. They purposely censor the GIA number of their diamonds to make it difficult for you to compare. lol.