GC Diamonds are GreekChat Diamond Sisters. Maybe a year (or was it two?) ago, a bunch of us regular posters got together and someone became the GC New Member Coordinator and we all got Diamonds. There were 2 or 3 in each Diamond Sister set. We did this because a few of our members never had any Diamonds when they were a collegiate- for whatever reason, either they were ancient dinosaurs (HaHa, Just kidding) and only had "Bigs" and "Littles", or they transferred out of a chapter before they were able to have a "little" diamond, or they just didn't talk to their Diamond Sisters from their own chapter anymore, or just because!
Macon Magnolias are the Phi Mu's and us. That is another purely GreekChat term. That was started 3 or 4 years ago when a couple of Phi Mu's and ADPi's were chatting about not having a name for the sororities founded at Wesleyan in Georgia. Other groups who were all founded at the same school had names- Monmouth Duo, Farmville Four, so they wanted a name for our special bond too. See the following thread for how it actually got started:
http://www.greekchat.com/gcforums/sh...acon+Magnolias
Hope that helps and welcome back to GreekChat!