真正的王室寶物
這一支是畫面的字面版本：櫃子裡真的有那些東西。
noun · B2
The crown, sword, rings and other jewelled objects that a king or queen wears or carries at official ceremonies.
王室寶物（王冠、權杖等御寶）
核心畫面
A useful way to hold this: picture a room with a crown in a glass case, and on that crown one stone that catches the light before any of the others. Everything in the room is valuable, but a visitor's finger goes straight to that one. Both uses of the phrase live on that moment of pointing. In the plural you are naming the real royal objects; in the singular you are telling someone which single thing a shop, a town or a collection would show you first — and, quietly, that the owner is proud of it.
可以想成一個展示間：玻璃櫃裡有一頂王冠，而王冠上有一顆石頭，光線一照就先亮起來。整個房間的東西都很珍貴，但參觀的人手…更多收起
可以想成一個展示間：玻璃櫃裡有一頂王冠，而王冠上有一顆石頭，光線一照就先亮起來。整個房間的東西都很珍貴，但參觀的人手指一定先指向那一顆。這個說法的兩種用法，都停在「先指向哪一個」這一刻。用複數時，指的是真正的王室器物。用單數時，是在告訴別人：一家店、一座小鎮、一批收藏，最先要拿出來給你看的是哪一樣——而且順帶透露，主人很以它為傲。From the word’s history
Wiktionary's first sense defines the phrase as "a prized possession or asset, originally one making up part of the royal regalia", which puts the royal objects first and the figurative use after it.
Wiktionary 的第一個義項寫成「珍貴的所有物或資產，原本指王室禮器的一部分」。這句話把順序講清楚了：先有真正的王室器物，比喻的用法是後來從那裡長出來的。
Wiktionary entry for crown jewel (kaikki:3f6f69a190036ae4:2230538426:4159), sense 0: "A prized possession or asset, originally one making up part of the royal regalia."
Two branches
最先被指出來的那一個
把手指移出王宮：任何一堆東西裡，都有那顆先亮起來的石頭。
noun · B2
The best, finest or most valuable thing that a person, a place, a company or a collection has — the one you would point to first if you had to show just one.
最寶貴的東西／鎮店之寶