(ט) וְלָ֣קַחְתָּ֔ אֶת־שְׁתֵּ֖י אַבְנֵי־שֹׁ֑הַם וּפִתַּחְתָּ֣ עֲלֵיהֶ֔ם שְׁמ֖וֹת בְּנֵ֥י יִשְׂרָאֵֽל׃ (י) שִׁשָּׁה֙ מִשְּׁמֹתָ֔ם עַ֖ל הָאֶ֣בֶן הָאֶחָ֑ת וְאֶת־שְׁמ֞וֹת הַשִּׁשָּׁ֧ה הַנּוֹתָרִ֛ים עַל־הָאֶ֥בֶן הַשֵּׁנִ֖ית כְּתוֹלְדֹתָֽם׃ (יא) מַעֲשֵׂ֣ה חָרַשׁ֮ אֶ֒בֶן֒ פִּתּוּחֵ֣י חֹתָ֗ם תְּפַתַּח֙ אֶת־שְׁתֵּ֣י הָאֲבָנִ֔ים עַל־שְׁמֹ֖ת בְּנֵ֣י יִשְׂרָאֵ֑ל מֻסַבֹּ֛ת מִשְׁבְּצ֥וֹת זָהָ֖ב תַּעֲשֶׂ֥ה אֹתָֽם׃
(9) Then take two lazuli stones and engrave on them the names of the sons of Israel: (10) six of their names on the one stone, and the names of the remaining six on the other stone, in the order of their birth. (11) On the two stones you shall make seal engravings—the work of a lapidary—of the names of the sons of Israel. Having bordered them with frames of gold,
(כא) וְ֠הָאֲבָנִ֠ים תִּֽהְיֶ֜יןָ עַל־שְׁמֹ֧ת בְּנֵֽי־יִשְׂרָאֵ֛ל שְׁתֵּ֥ים עֶשְׂרֵ֖ה עַל־שְׁמֹתָ֑ם פִּתּוּחֵ֤י חוֹתָם֙ אִ֣ישׁ עַל־שְׁמ֔וֹ תִּֽהְיֶ֕יןָ לִשְׁנֵ֥י עָשָׂ֖ר שָֽׁבֶט׃
(21) The stones shall correspond [in number] to the names of the sons of Israel: twelve, corresponding to their names. They shall be engraved like seals, each with its name, for the twelve tribes.
וְרַבִּי נְחֶמְיָה שָׁמִיר לְמַאי אֲתָא מִיבְּעֵי לֵיהּ לְכִדְתַנְיָא אֲבָנִים הַלָּלוּ אֵין כּוֹתְבִין אוֹתָן בִּדְיוֹ מִשּׁוּם שֶׁנֶּאֱמַר פִּתּוּחֵי חוֹתָם וְאֵין מְסָרְטִין עֲלֵיהֶם בְּאִיזְמֵל מִשּׁוּם שֶׁנֶּאֱמַר בְּמִלּוּאֹתָם אֶלָּא כּוֹתֵב עֲלֵיהֶם בִּדְיוֹ וּמַרְאֶה לָהֶן שָׁמִיר מִבַּחוּץ וְהֵן נִבְקָעוֹת מֵאֲלֵיהֶן כִּתְאֵינָה זוֹ שֶׁנִּבְקַעַת בִּימוֹת הַחַמָּה וְאֵינָהּ חֲסֵירָה כְּלוּם וּכְבִקְעָה זוֹ שֶׁנִּבְקַעַת בִּימוֹת הַגְּשָׁמִים וְאֵינָהּ חֲסֵירָה כְּלוּם תָּנוּ רַבָּנַן שָׁמִיר זֶה בְּרִיָּיתוֹ כִּשְׂעוֹרָה וּמִשֵּׁשֶׁת יְמֵי בְּרֵאשִׁית נִבְרָא וְאֵין כׇּל דָּבָר קָשֶׁה יָכוֹל לַעֲמוֹד בְּפָנָיו בַּמֶּה מְשַׁמְּרִין אוֹתוֹ כּוֹרְכִין אוֹתוֹ בִּסְפוֹגִין שֶׁל צֶמֶר וּמַנִּיחִין אוֹתוֹ בְּאִיטְנִי שֶׁל אֲבָר מְלֵיאָה סוּבֵּי שְׂעוֹרִין
The Gemara poses a question: And according to Rabbi Neḥemya, who maintains that they used iron tools even in the cutting of the stones for the Temple, for what purpose did the shamir come? The Gemara answers: It was necessary for that which is taught in a baraita: These stones in the breastplate and ephod, upon which were inscribed the names of the tribes, they may not be written on with ink, because it is stated: “Like the engravings of a signet” (Exodus 28:21), which means the names must be engraved onto the stones. And they may not be scratched on with a scalpel [izemel], because it is stated: “In their full settings” (Exodus 28:20), indicating that the stones must be complete and not missing any of their mass. The baraita continues: Rather, one writes the letters on them in ink, and shows them, i.e., he places the shamir close to the ink markings from outside, without having it touch the stones, and they split open along the lines of the ink of their own accord, like this fig that splits in the summer without losing anything of its mass, and like this field in a valley that cracks in the rainy season without losing anything of its mass. The shamir was used in this way for these engravings. The Sages taught: This shamir, its size is that of a barleycorn, and it was created in the six days of creation, and nothing hard can withstand it. In what is it kept, so that it will not break everything in the vicinity? They wrap it in tufts [sefogin] of wool and place it in a leaden vessel [itenei], full of barley bran, which is soft and will not be broken by the shamir.