Since I have a good example of each in my incubator right now I thought I'd post it so you can see the difference. Hopefully the picture shows it good enough.
The eggs on the lower left are fertile. Notice how white they are. When we talk about "chalking" this is what we're talking about.
The eggs on the upper right are sort of translucent and not white. These are not fertile and haven't chalked.
![eggs 8-7-16.jpg eggs 8-7-16.jpg](https://data.www.tortoiseforum.org/attachments/168/168992-22bbc961e8721509eeb600dc3c9ee67a.jpg)
The eggs on the lower left are fertile. Notice how white they are. When we talk about "chalking" this is what we're talking about.
The eggs on the upper right are sort of translucent and not white. These are not fertile and haven't chalked.
![eggs 8-7-16.jpg eggs 8-7-16.jpg](https://data.www.tortoiseforum.org/attachments/168/168992-22bbc961e8721509eeb600dc3c9ee67a.jpg)