The Weekly Shtikle Blog: The Weekly Shtikle

In the listing of the stones on the choshen (28:17-20) there is a difference between the last row and the other three. The last row is Tarshish ve'shoham ve'yashfeh. There is a vuv before the second stone as well as the third. In the other three rows, the vuv appears only before the last stone. Meshech Chachma points out that the reason for this is, as we find in kriyas shema, that certain groups of words where the first word ends with the same letter as the second word begins, such as "al levavchem" and therefore must be very carefully differentiated. So, too, here tarshish and shoham have the same problem. Therefore, in order to differentiate between the two, HaShem told Moshe "Tarshish ve'Shoham" so he would not get mixed up. The difficulty is, however, that in parshas Pekudei (39:13) the list does not contain a vuv before shoham. Although Meshech Chachma does make mention of this fact he does not clearly indicate why that is. R' Baruch Epstein, in Baruch She'amar, provides an answer. In Tetzaveh, HaShem is talking to Moshe. Therefore, it was important to differentiate between the two so that there is no confusion. In Pekudei, however, the Torah is merely giving its own recount of events so it was not imperative to place a vuv in the middle.

However, I heard the following challenge to Baruch She'amar's understanding. At the beginning of Shemos we seem to find a similar phenomenon. When listing the sons of Yaakov a vuv is only used for the last name in each pasuk. Except for pasuk 1:4, where there is a vuv before Naftali. It would seem that this is to differentiate between the nun at the end of Dan and the nun at the beginning of Naftali. However, here it seems only to be giving a recount and there is no dialog between two parties. By the above reasoning, there should be no reason to separate the names with a vuv. See the comments on this Dikdukian post for further discussion.