Learn how to choose crystals and stones.
It's often said that crystals and stones choose us, rather than us choosing them. This may well be, although I tend to think it's a mutual choosing process, and the same holds true for crystals and gemstones jewelry.
Either way though, the key to choosing crystals and stones is to use your intuition. Do what feels right to you. You may feel a tingling sensation, a sensation of well being, a sense of "that's one I need to get", or you may just know inside that it's a stone that wants to come be with you. This holds true where ever you may be purchasing stones, online as well as at a shop or fair locally.
Before purchasing a crystal or stone jewelry or the stones themselves, online or locally, take a moment quietly to ask your intuition or higher self, "Is this a right crystal, stone, or jewelry for me at this time?" If you get a sense that they are, go ahead with your purchase. If you get a sense that something isn't quite right, or a negative feeling, pass that stone or crystal by and keep looking for the right ones.
Trust your intuition and you'll be happier with your crystals and stones.
Whether it's us choosing the stones or them choosing us, our higher self or intuition is the best guide to determine which are the right crystals and their jewelry to acquire.