THanks for the price updates and also, explaining what was driving the increase.
I'm actually going to report it just "as is". I don't want this guide to be dictated by my opinion but by actual data from the marketplace. If, over time, people are only willing to pay 300-500 for a birthstone, then the 900, and 1000 "aberrations" will just drop off range. For now, that's what the market is.
(And as a random FYI, there was a time when birthstones went in the 1000-2000 BTB range because it was really uncertain whether they would repeat in cycle. So anything can happen, really...)