While I know a great deal about gemstone's, having learned it as a kid from family that were into lapidary, there are times additional resources need to be tapped. Practical knowledge is great for simple everyday use, but I have been finding since we started Entwined Vines Jewelry that additional information beyond the practical is necessary to meet FTC guidelines.
The best source of information and where I spend a great deal of time is the local lapidary shops. Fortunately, living in the Pacific Northwest we have several, the largest being Ed's House of Gems.
Don't discount the smaller places though, they tend to specialize and the owners tend to be the one doing the rock hounding. The only disadvantage with the small lapidary shops that I have found is they are not always open at convenient times.
Books are another great source of information on rocks, minerals, and gemstones. Before buying books at random, sit down and decide what it is you are looking for in a book. Stones books can be about healing, home placement, and mineral content to name a few. You can spend lot of money before you find the perfect book, so I also recommend seeing what is available at your local library and perusing as many as you can before purchasing.
Here are a few titles from my collection:
1.) Crystals by Jennie Harding
2.) Cunningham’s Encyclopedia of Crystal, Gem & Metal Magic by Scott Cunningham
3.) The Illustrated Guide to Crystals by Judy Hall
4.) The Metaphysical Book of Gems & Crystals by Florence Megemont
Lapidary or rock clubs are another great source when tyring to find or identify stones. While not all clubs are listed on the Gem and Lapidary Clubs website, it is definitely a good place to start. To find ones near you that are not listed check with your local community center.
Another great source of information are institutes and associations, here are a few to get you started. While most of these appear to only deal with diamonds that usually isn't the case and if they can't help you they will know who can. I wonder through them occasionally, yet have not had the need to contact them myself.
Gemological Institute of America
International Gemological Institute
American Gem Society
Publications and journals can become an expensive habit, but oh so useful.
Gems & Gemology
Lapidary Journal Jewelry Artist
HardAssets.com -- found this by accident, has a lot of information and recommends books and other source sites.
While these are sites and publications I have used in the past, their accuracy is not something I can guarantee. Each time I am doing research I start from the beginning as if I don't know where to look. I have found that researching as if I know nothing leads me to the information I am looking for better than researching with a preconceived notion and I spend to much time in the lapidary shops.
Do you have any suggestions to add?