In the seventeenth century the two royal houses ceased the (i) ________ practice of wearing the (ii) ________ crown jewels of their (iii) _______ to public events.

The phrase "crown jewels" gives us an important clue. Wearing the crown jewels in public events is definitely an ostentatious practice. Not panoramic or palpable. But even if we considered it a panoramic practice, there is no reason to cease a panoramic (or palpable) practice. But definitely a strong case can be made for ceasing an ostentatious practice or a practice characterized by a pretentious or showy display which is designed to impress.

Clearly if the practice was showy and designed to impress, the jewels have to be opulent - costly and luxurious.

Crown jewels of their hierarchy is vague and does not make sense.

Royal houses don't have their own oligarchies, so it does not make sense to say they wore the crown jewels of their oligarchy.

But progenitors makes sense, since in the seventeenth century most of the royal wealth was inherited.