The only thing that the following three outfits have in common is that they are black, they are elegant, and they are free! Each is a free group gift, with a free group join.
First we have a lovely Lia black chemise with matching black pants, a free group gift from Clef de Peau. Perfect for the SL ladies who lunch! Simply join the Clef de Peau group for free, and click on the gift box on the ground at this SLURL:

The Lia outfit comes with a HUD to change the arm and leg cuffs to one of several different colours, including black (as I did with the pants this avatar is wearing in the picture above, to make them all one colour).
This is the beautiful Pelaides full-length ballgown; with materials enabled, it truly shimmers! Here I paired it with a white fur stole from Glitzz (one of their group gifts, the Glitzz group currently costs L$250 to join):

You can pick this up for free from the JR Wolf Creations store, just click the panel to join the group for free! The gown comes with a HUD with six different ombre tones, as shown, and let me tell you, it’s simply stunning (these still pictures simply do not do it justice!):

But I think I left the best for last! Here Vanity Fair models the sexy little black Kali dress, simple but elegant, perfectly paired with some chunky costume jewelry from JUMO (the Olivia earrings and necklace, a previous Advent gift):


(As an aside, the champagne glass with the Bento hand pose is my new favourite party prop! I bought it as part of the Celebration Champagne set, which includes two of these poses as well as champagne bottles and buckets, at Hive for only L$250. I just love it!)
The Kali dress is one of many free gifts you can pick up at the Apple Blossom & Seeds store, just click the black panel to join their group for free, and scoop up many lovely items of women’s clothing! Here’s the exact SLURL to find the group gifts wall, and the red arrow points to the Kali dress that Vanity Fair is wearing:

Happy freebie shopping!