Perhaps show us what you are trying to achieve and what you have achieved so far.
Is the egg raw or cooked? Fried, boiled, poached? Separated from the white or still embedded in it? All of these things can have a dramatic effect on how the yolk looks.
Fried egg?
You could try 2 things, some subsurface scattering with a darker more redish colour.
I also made a copy of the egg and scaled it up a bit and gave it a glass texture with a little diffuse over the white and masked it with a sphere gradient so it does not whiten the yolk. This gives an outer transparency a bit like what people do for eyes.
One egg has the white and yolk material the other has a glossy transparent material (made with a glass shader and a diffuse shader. This is to simulate the uncooked transparent “slime” on the top of a fried egg.
Yes that was my idea with the second “transparent egg” it needs some more work but I think it is better to treat that “semi” transparent layer as a separate object (you could combine the 2 objects) I will do some more experiments to see if I can get it more realistic (maybe volume absorption).
Your reference is a raw egg do you want it raw or fried?