I am writing this post at the risk of sounding like a crazy person, hope it helps those who are open to it. My understanding of the theory behind Gem Healing is basically that stones emit energy, just as everything else does, and by carrying a stone you are putting yourself in the frequency of that stone. Each stone has its own unique chemical properties and characteristics. To me, if quartz can move a clock with its electrical vibration it stands to reason that quartz and other stones can affect our electromagnetic field as well.
The problem though, is finding accurate information about which stone has which effect on us. I have 3 books that all name different stones for different areas of life. I've seen ads in catalogs that claim certain stones have healing powers that I haven't witnessed. There is information on the internet, other books, and even ebay, all attributing different powers to the same stone. To get off the subject for a moment, I also have found this with other metaphysical subjects. In Feng Shui I've seen conflicting advice, and even Astrology has different methods that can change a whole chart.
So, what I do is experiment and use the information and methods that I feel are most accurate and disregard the rest. That said, I have seen some definite effects from stones, sometimes curious ones. On several occasions I have been wearing a stone, didn't really notice any effect on me, but other people commented that I had the attributes of the stone I was wearing.
CAUTION - Please, Please, don't go out and buy or order a bunch of jewelry. The effects of these stones are apparent whether it is a rough, unpolished stone for $2.00 or a $400.00 gold ring. Size and condition also don't matter, so a small stone with scratches is fine. Please use this information wisely.
Okay, one day I was at work and carrying an orange sapphire with me. My most reliable source associates orange sapphire with learning and becoming an expert in your intellectual field. I personally didn't notice any special effect on me, but someone at work asked me if I was a college student. Not so unusual, but I was well past the age of a typical college student. Another time with the same stone, a different person was going on about how smart I was because of an idea I had. Flattery is not this person's typical behavior.
Another stone I've had this type of experience with is pink topaz. While carrying a pink topaz, which is said to foster ethics and moral character, 2 people said that I was an honest person. One more time to tell you about; when I was carrying tsavorite garnet and connemara marble someone asked me if I was happy, both stones are said to promote happiness.
These aren't coincidences to me. The only other explanation is that I believed that they would have those effects and was emitting that energy on my own, I can't say for sure.
As far as effects I myself have noticed, emerald is associated with communication and I have noticed that I sometimes talk more when carrying one. I believe quartz can help keep the body running smoothly, it doesn't hurt to try it, but if you have an illness always see a doctor, and you can use quartz in conjunction with doctor's treatment and advice. If you have a problem area try keeping the quartz near that area. For example, if you are prone to sinus problems try lying down with the quartz resting on your forehead or cheeks. Some varieties of quartz are amethyst, citrine, prasiolite, and clear rock crystal, just be sure the clear crystal is genuine quartz. To state the obvious, never eat gemstones, just had to say it, you understand. And I find garnet helps me be more motivated to get things done. To sum up I will list the stones and effects.
ORANGE SAPPHIRE - Learning and Becoming an Expert in an Intellectual Field
PINK TOPAZ - Ethics and Moral Character
TSAVORITE - Happiness
CONNEMARA - Happiness
EMERALD - Communication
QUARTZ - Physical Healing
GARNET - Motivation
SPESSARTITE GARNET - Motivation around the house
RHODOLITE GARNET - Motivation in work or career