I am not sure I would re-do the whole DMS bulk sample reject. I think it makes sense though to do a full caustic analysis of all sills, even the top layer, at the bulk sample location. This will help form a baseline for a locatioin where no diamonds were recovered, and let us know if it is worth doing a bulk sample deeper than the first sill.
If the caustic of the fist sill shows more diamonds than the bulk sample, then I would audit the dms reject pile.
Just my thoughts on this.
Ted