The collection for the Tabernacle concludes by detailing the unique contribution of the tribal leaders: the precious stones set into the High Priest's garments. Placing this detail at the very end of the list reflects a deliberate progression, moving from the donations of the men, to the women, and finally arriving at the leaders [קאסוטו, אור החיים].
In the original Hebrew text, the title of the leaders is spelled with a missing letter. The primary approach among commentators is that this omission serves as a subtle criticism of their behavior. When the call for donations was first announced, the leaders decided to wait. They declared that they would allow the general public to contribute first, and then they would personally supply whatever was missing to complete the project. However, the people's enthusiasm and generosity were so overwhelming that there was almost nothing left to give, save for the precious stones and oil. Because of their delay and lack of urgency, a letter was deducted from their title.
This delay was not merely born of laziness, but of pride. The leaders wished to act as wealthy patrons, elevating themselves above the rest of the nation. They failed to understand that personal responsibility requires rushing to fulfill a Commandment just like any ordinary person [כלי יקר, רבנו בחיי, רש״ר הירש, חומש קה״ת, צאינה וראינה]. As an atonement for this haughtiness of the heart, the leaders specifically brought the precious stones that were destined to rest over the heart of the High Priest [רבנו בחיי, צאינה וראינה]. Taking a completely different approach, some explain that the missing letter simply reflects their status at the time; they had not yet been officially appointed as leaders by God, but were merely acting with the agreement of the tribes [העמק דבר].
How the leaders acquired such precious gems in the barren wilderness is a matter of discussion. The natural explanation is that when leaving Egypt, the Israelites took wealth according to their social standing. Given their high rank, the leaders carried vast treasures with them, from which they now donated [אבן עזרא, חזקוני, הטור הארוך, ביאור שטיינזלץ]. Conversely, a broader tradition connects the Hebrew word for leaders to the word for clouds. According to this view, the miraculous clouds of glory rained down precious stones and pearls from the heavens along with the daily portion of Manna, and the leaders gathered them for their contribution [רא״ש, רבנו בחיי, צאינה וראינה, תורה תמימה, דעת זקנים, פרדס יוסף]. Bridging these ideas, some suggest that the heavens only release their wealth in the merit of a community that gives charity properly. Because the Israelites donated with such a generous spirit, the clouds responded by showering down the abundance that enabled the leaders to bring the stones [כלי יקר].
The specific division of the stones they brought reflects a dual purpose. The two shoulder stones, upon which the names of all the tribes were engraved together, were brought as a joint partnership by all the leaders united. In contrast, the stones meant for the breastplate were brought individually. Each leader personally contributed a single stone, which would eventually bear the name of the specific tribe he represented [רשב״ם, רא״ש, הדר זקנים, בכור שור, חזקוני].