A dry socket should look off white in color but it also depends on the lighting. It could range anywhere from a light yellow to white color, which still fall within the realm of "off white".
The reason why it is that color is because that is the color of bone. Essentially what a dry socket is, is exposed bone without a blood clot nor granulation tissue. Therefore all that you see when you look in the extraction socket is exposed bone.
Here is what a dry socket looks like in the mouth:
As you can clearly see in the picture above, is part of the exposed bone that is showing through. That is essentially what a dry socket is, delayed healing with exposed bone.
The color of bone
Therefore the color of a dry socket is basically the color of what bone looks like. Here is a video of the human mandible (lower jaw).
The video above shows the mandible of a cadaver which comes from a deceased human, hence why they're wearing gloves. The color of the jaw bone looks more yellow than white but you should take into consideration that, that color isn't what "fresh bone" would look like in a living human being.
Over time after being treated with chemicals, the color will yellow a bit. Therefore, you can expect it to look more white than what you see in the picture.
Can a dry socket look any other color?
In case you were curious as to whether or not it can look a different color such as red, grey, black or white it wouldn't. If you saw those other colors it would mean that you don't have dry socket and that you probably have something else!
Red inside of the socket
If you're seeing red inside of the hole, it is definitely not a dry socket because the red signifies that there is a blood clot present. If you have a clot that is forming it means that you DO NOT have dry socket.
The very definition of that condition is a LACK of a blood clot. Therefore, if it looks red you are well on your way to healing and that is a good sign.
Grey inside of the socket
Your socket shouldn't really look grey because there isn't anything that would make it that color. You could be mistaking white stuff in the extraction hole for it to being grey. That is simply granulation tissue and nothing to be concerned about.
Socket looks like a black hole
If the hole just looks pitch black, that isn't necessarily a bad sign. It could very well just mean that the tooth is in the beginning stages of healing. It does not imply that you have a dry socket because it would never look black.
The reason why the socket can look black is because light doesn't always reach into depths of the extraction hole. Think about it, your dentist literally has to shine an overhead light down into the hole to see what is there. If you're not using a light to look into the hole, it would simply look black.
This is especially more pronounced if you're trying to look into a wisdom tooth hole. In addition to how deep the socket can be, the wisdom teeth are also really far back in your mouth so that makes it all the more difficult for light to reach there. Thus, if you were ever wondering why your wisdom tooth hole looked black, that is the reason why!
White stuff inside of the extraction hole
If you are seeing white stuff where the tooth was extracted, that is actually a very good sign. That white stuff is basically granulation tissue which implies that the socket is undergoing proper healing.
Over time, the hole should close and you'll no longer notice anymore of the granulation tissue.
You can distinguish this from food being stuck in the hole by if you rinse and it doesn't come out. You can also try flushing it with a water flosser to see if it dislodges. If it doesn't and you're not in any pain, it is most likely just granulation tissue. In other words, you do not have a dry socket because it shouldn't look like white stuff.
Learn more: White stuff in tooth extraction hole.
Other potential white stuff
Just so that you are aware and careful but if you have white stuff oozing out of the socket, that is actually not a good sign. Granulation tissue looks white but it should not ooze out. If you find white liquid oozing out that could be pus.
The presence of purulence indicates that there is an infection. Thus, if you see white liquid coming out of the socket and it smells/tastes bad, you most likely have an infection!
You should go back in to see your dentist immediately to have it addressed. It may need to be cleaned out and irrigated. You'll most likely leave with some antibiotics and an antibiotic rinse as well.
Overall, a dry socket should look approximately off white in color. Although it can range from a little more white to a little bit more yellow and that's all completely normal.
It looks that color because the condition is basically exposed bone that is not healing so what you see is just the bone underneath. Therefore whatever color your bone is, is the color that you would see inside of the socket.
If you see any other color aside from the off white, it would mean that it is something else. Most of the time it is good news because it means that you don't have a dry socket and that it is probably just healing.
Aside from the color, a tell tale sign that you may have the condition is if you're experiencing extreme pain. The exposed bone is extremely sensitive and will elicit pain if water or food touches it. That is a definite give away for if you have it or not.
Nonetheless, we always do recommend following up with your dentist who did the extraction. That way you get a peace of mind that it is healing normally as it should.