Or HaChaim on Exodus 25:7/אור החיים על שמות כ״ה:ז׳

1 אבני שהם ואבני מלאים, onyx stones, and stones to be set, etc. Why were these items mentioned only after the other eleven types of materials? They should have been listed even ahead of gold and silver seeing they are of superior value! Perhaps the reason is that the princes who contributed these stones did so only after the people had contributed all their donations. We are told in Bamidbar Rabbah 12,16 that G'd was so displeased with the tardiness of the princes in bringing their donations that the Torah does not even spell the word נשיאים fully in the relevant passage but omits the letter י in their title (compare Numbers 7,10). Mentioning their contribution last was a punishment for their tardiness.

2Another reason for mentioning these stones last may be the fact that they were not used as part of the Tabernacle but only as part of the priestly garments. We have learned in Yuma 69 that it was permitted to make use of these priestly garments, i.e. that one was not guilty of מעילה, trespass, when having made profane use of such garments. Maimonides writes in chapter five of the laws dealing with such trespasses that the priestly garments are not subject to such laws. It follows that the sanctity of the priestly garments cannot be compared to the sanctity of the Tabernacle itself. It is quite logical then that these gemstones, though intrinsically more costly than gold and silver, should be mentioned last in the order of contributions listed by the Torah. While it is true that some of the other eleven materials also served to make the priestly garments, their principal function was to serve as materials from which to construct the Tabernacle itself.

3Moreover, there is an opinion cited in Yuma 75 according to which these gemstones originated in the celestial spheres and their attainment did not represent an effort on the part of their owners nor did their being given away represent a loss to those who donated them inasmuch as they had never toiled in order to acquire them.