No.
1
Order, not measurement
Each chip outranks the one before only by scratching it — talc to diamond is a sequence, never a ratio.
No.
2
The specimen is the unit
No instrument is required. The ten reference minerals carry the scale in the hand, mounted on cool chart paper.
No.
3
Gaps are uneven on purpose
Step 9 → 10 spans a wider true hardness than any earlier step — the row hides its own steep end.
No.
4
Colour is muted by design
Specimens read as earth-grays so the eye judges the scratch line, not the mineral's tint.