These silkworm eggs are starting to turn “blue” – the developing worm inside separates from the shell, and they get a hazy lighter color. About half the eggs in this photo are blue – the others are likely nonviable.
If you look really close, and you’ve got a good magnification on your camera or hand lens, you can see the caterpillar curled inside the egg.
These have reached the head pigmentation stage; you can see the little dark heads. They’ll hatch within another day or two.