BLUE 420MHz was 230 ohms
ORANGE 820MHz was 130 ohms
I would interpret that as indicating the tip capacitance is approximately 1.5pF.
For reference, here's a scan of the interesting bits of my hp10020 probe, 10:1, 500 ohms, 1.5GHz, <0.7pF, millimetre scale.
The metal part contains the 450ohm resistor and when inserted into the bayonet only the cable's screw thread is visible. The bayonet makes contact with the wide part of the metal shank (see the diagonal "score" marks) plus the end of metal part's narrow shank.
The metal part is light and there are visible external air gaps inside the plastic part - I interpret this as minimising material with Er>1 so as to minimise tip capacitance.