Liberty Ross -- Wedding Ring Fake Out [UPDATE]

Liberty Ross looked hot and forgiving Tuesday night ... as she was spotted wearing her wedding ring for the first time since her philandering husband Rupert Sanders was caught cheating with Kristen Stewart.

Liberty was wearing leather pants and her giant diamond ring outside the Chateau Marmont.

Rupert -- who we're told has been "desperate" to save the marriage -- has been seen wearing his ring in the past, but until now Liberty's gone sans her commitment bling in public.

Perhaps all is forgiven.

12:40 PM PT -- Additional photos have just surfaced ... showing Liberty's new ring is actually on her middle finger. NOT her ring finger. Ergo, it's not a wedding ring after all.