The tribes as the root of all jewels

בחשן ואפוד תפתח כו' שמות בני ישראל כו'.

Regarding the choshen and ephod: "You shall engrave… the names of Bnei Yisrael…" (cf. Shemos 28:9-21)

The names of the tribes were engraved upon the precious stones of the Kohen Gadol's breastplate and ephod. The Sefas Emes asks what these twelve stones truly represent.

כי בודאי י"ב אבנים אלו הם שורש כל אבנים טובות.

For certainly these twelve stones are the root of all precious stones.

The twelve stones of the choshen are not merely beautiful gems; they are the spiritual source-root from which the value of every precious stone in the world is drawn.

ולכן אבנים טובות תכשיטין הם בעולם ע"י שכל תכשיט הבריאה הם השבטים לפני הבורא ית'.

And therefore precious stones are ornaments in the world, because all the adornment of creation is the tribes before the Creator, may He be blessed.

Gems serve as ornaments here below only because they reflect a higher reality: the true "jewelry" of all creation is the Shevatim (the tribes of Yisrael), who are the adornment standing before Hashem.

וז"ש תפתח. כי השבטים הם שורש אלה האבנים.

And this is the meaning of "You shall engrave" (tiftach) — for the tribes are the root of these stones.

The word tiftach (literally "open/engrave") hints that engraving the tribes' names into the stones reveals their inner root: the Shevatim are what give these gems their essence.

והעיקר זכרון הוא יוסף לכן באפוד היה רק שוהם אבנו של יוסף.

And the essential remembrance is Yosef; therefore on the ephod there was only the shoham, the stone of Yosef.

The core point of "remembrance" centers on Yosef. That is why the shoulder-stones of the ephod were the shoham — Yosef's particular stone — set apart from the rest.

ובאמצעיות אבנו של יוסף. כל הי"ב אבנים מתאחדין בשורשיהם:

And by means of Yosef's stone, all twelve stones are united at their roots.

Yosef, the tzaddik who sustains and binds, serves as the channel through which all twelve tribes are joined back to their common source — so through his stone the entire choshen is unified at its root.

Summary: The twelve stones of the choshen are the root of all precious stones, for the true adornment of creation is the Shevatim standing before Hashem. Engraving their names reveals this inner root, and through Yosef's stone — the shoham, the essential point of remembrance — all twelve tribes are bound together and unified at their source.