Welcome to the coop. We were trying to discuss this colour in this thread:http://www.the-coop.org/forums/ubbthreads.php?ubb=showflat&Number=105093
In my opinion the e-locus is one of the eb
-like ones(e^bc or e^s ) and definitely Pg. The cocks have often an extensive leakage of pheomelanin on the breast, so perhaps Mh and then diluted by Di??(hen is rather light gold). It's just only a speculation. Somebody just needs to outcross them to e+ and see what segregates. Otherwise you will be guessing to the end of time.