Beg to differ.  Kala Zeera is black cumin and is from the same plant genus as White Cumin - Sufaid Zeera.  Kalonjii and Nigella are related to Onion seed (same genus but different plants) and are not related in any way to Cumin.  Hope this clears things up.

However CC the idea of black cumin in Shai Tikka is vert intriguing and you may just have hit on the subtle falvour in this dish; thanks.

CP