The Shoham Stones

The Kohen Gadol wore two stones on his shoulder plates - each stone had the names of 6 of the 12 tribes.  These stones are introduced as the שְׁתֵּי אַבְנֵי-שֹׁהַם - which has a gematria of 1118.  In Chapter 28 of Shemos, it lists the priestly vestments to be worn during service in the Mishkan.  While the Torah doesn't provide reasons for most of the items worn by the Kohen Gadol, the Torah devotes a pasuk explaining that the Shoham Stones are the "Stones of Remembrance" and makes 2 references to it in the same pasuk (28:12):

יב  וְשַׂמְתָּ אֶת-שְׁתֵּי הָאֲבָנִים, עַל כִּתְפֹת הָאֵפֹד, אַבְנֵי זִכָּרֹן, לִבְנֵי יִשְׂרָאֵל; וְנָשָׂא אַהֲרֹן אֶת-שְׁמוֹתָם לִפְנֵי יְהוָה, עַל-שְׁתֵּי כְתֵפָיו--לְזִכָּרֹן.

It is unclear what is so special about these stones that of all the items the Kohen wears (including other stones in the Choshen), only the Avnei Shoham are the Remembrance Stones.

It's interesting to note the spelling discrepancies between Chapter 28, where Hashem explains to Moshe what the Kohen needs to wear, and Chapter 39, where Betzalel actually makes the clothing.  See the highlighted words below:

Chapter 28:

ט  וְלָקַחְתָּ, אֶת-שְׁתֵּי אַבְנֵי-שֹׁהַם; וּפִתַּחְתָּ עֲלֵיהֶם, שְׁמוֹת בְּנֵי יִשְׂרָאֵל.

י  שִׁשָּׁה, מִשְּׁמֹתָם, עַל, הָאֶבֶן הָאֶחָת; וְאֶת-שְׁמוֹת הַשִּׁשָּׁה הַנּוֹתָרִים, עַל-הָאֶבֶן הַשֵּׁנִית--כְּתוֹלְדֹתָם.

יא  מַעֲשֵׂה חָרַשׁ, אֶבֶן--פִּתּוּחֵי חֹתָם תְּפַתַּח אֶת-שְׁתֵּי הָאֲבָנִים, עַל-שְׁמֹת בְּנֵי יִשְׂרָאֵל; מֻסַבֹּת מִשְׁבְּצוֹת זָהָב, תַּעֲשֶׂה אֹתָם.

יב  וְשַׂמְתָּ אֶת-שְׁתֵּי הָאֲבָנִים, עַל כִּתְפֹת הָאֵפֹד, אַבְנֵי זִכָּרֹן, לִבְנֵי יִשְׂרָאֵל; וְנָשָׂא אַהֲרֹן אֶת-שְׁמוֹתָם לִפְנֵי יְהוָה, עַל-שְׁתֵּי כְתֵפָיו--לְזִכָּרֹן.


Chapter 39:

ו  וַיַּעֲשׂוּ אֶת-אַבְנֵי הַשֹּׁהַם, מֻסַבֹּת מִשְׁבְּצֹת זָהָב, מְפֻתָּחֹת פִּתּוּחֵי חוֹתָם, עַל-שְׁמוֹת בְּנֵי יִשְׂרָאֵל.

ז  וַיָּשֶׂם אֹתָם, עַל כִּתְפֹת הָאֵפֹד--אַבְנֵי זִכָּרוֹן, לִבְנֵי יִשְׂרָאֵל:  כַּאֲשֶׁר צִוָּה יְהוָה, אֶת-מֹשֶׁה.

All told, in the otherwise identical words used in both descriptions, there is an extra "Hay" and 4 extra "Vav"s used between Chapter 28 and Chapter 29.