[Pavel Chaloupka]

The eggs being yellow does not have to necessarilly mean that they are doomed already. A lot of different dyes are capable to penetrate the chorion and stain the eggs to some extend, it is only that unfertilized eggs will get stained much more. So there is still hope. If you use any type of organic dye like acriflavine or other dyes from that group, methylene blue and such stuff, it will always stain the eggs.