Parashas Tetzaveh · Passuk 28:20
Chabad.org — English translation + Rashi
Torah Temimah points to Sotah 48b.
Sefaria — Exodus 28:20
Sefaria — Sotah 48b
E-Daf — Sotah 48b
English: Regarding the stones of the breastpiece, the baraisa teaches that they were not engraved with a graver. The wording “in their setting” is understood to indicate that the stones were to remain complete rather than being cut with an iron tool.
On the daf / in context: See the cited source for the full section.
Derash on the verse.
The verse’s “in their settings” is used to teach a specific rule about the preparation of the stones: they were not engraved with an iron instrument.