Fascinating. Indeed looks like the drop at the bottom of the tassel in the hair could be Cullinan VI (or VII...?). Perhaps a bit clearer in this version after photo quality correction:
--Previous Message-- : : I wonder what else is on her head besides : the veil and small diamond crown of Queen : Victoria? : : The drop looks like Cullinan VI. : : Royal Collection number 2106357 : : : :