There are many books on the healing properties of precious and semi precious stones as well as crystals.
I disagree, anyone can use them and receive their benefits for everyday or occasional use. The reason that some people may feel they aren't working for them is because the energy is subtle. They don't give you a charge like sticking your finger in a wall socket for example or a high like drugs. If you are open and sensitive, then you will feel a difference in the subtle energy from one stone to another.
My article
Stone Energy | Ocean Of Perspectives has pictures with a short summary of benefits for some of the more popular stones. There's too many to write about each and every stone available in the world. I would explode my allotted data storage, lol. One benefit of quartz crystal is that of providing purification of the physical, mental and spiritual bodies. The list is quite extensive just for quartz crystal.
Regarding illnesses, I do not recommend trying self treatment for health conditions. Do get the required medical treatment. Don't rely on practices such as Reiki, crystal and stone healing, etc, only; they will and do work with medical treatments. I added that to make it clear that I wasn't saying that everyone can cure their own health conditions.