Sorry, don't know the part # for the White Diamond but..
can get the all "Chrome" grill and new grill emblems from www.gmpartsdirect.com ..
I'm sure if you email them they can help you with the part # for the White Diamond.
White Diamond might be more but last I knew these were the prices.
Chrome Grill= match Silver Paint # 12336042 .. $239.22
Chrome Grill= match Black Paint # 12336039 .. $239.22
Wreath # 88944248 .. $20.92
Crest # 88944263 .. $21.34