The current colors in box are Black, Bleu Saphir, Rouge H, Brique, and Vert Fonce. Vert Foncé was produced in the smallest quantity for a particular event, but they have been trickling in stores outside France lately. I have only heard of thé Vert Foncé being produced for the Kelly with gold hardware. I definitely have my eyes set on a Vert Foncé, but I am unsure if it even is possible.
I was offered a Black and hinted to a Rouge H all in the Kelly 28 size. I find the mini Kelly to be too small, but was told that I could more easily get a mini Kelly in box in an array of colors.
Fun fact, I learned that out of 100 Birkin and Kelly produced, only 3 are made in heritage leathers.