How we grade what we sell
The tiers aren't a quality ranking. A quality-approved tumble isn't a lesser object than a hand-selected specimen; it's a different kind of object, checked the way that kind of object needs checking.
What the tiers measure is how closely a piece is examined before listing, matched to the piece, not used to rank it. It's separate from how a piece is listed; every specimen is listed individually as the exact piece you'll receive, whatever tier it was assessed under. Only high-volume material is shown as an example rather than the exact piece.
A single rare specimen is examined on its own. A run of identical tumbles is checked by sampling the batch. Pricing one the way you'd price the other would misrepresent both. So we don't. Each tier is named for how the check is done.