Before buying your gem stone, do a little research. Learn the magickal colors and properties of each stone. Decide before you buy which stone it is you will want to work with . Once you have decided this you will find that most store owner sell their stones by in bulk. Usually there will be many of the same stones in one bin. So how do you choose the right one? First look at the stones. They will be different shades in their coloring and different shapes as well. Think what you are wanting to use the stone for and then see which ones catch your eyes first. Pick up these stones one by one and hold it in your power hand. Now, close your eyes and imagine you are a vacuum. Try to "pull" the energy from each stone that your eyes were drawn to. You will find that some stones give off more energy than others. Stones are like people and have their own personalities. With sight, touch and feeling you will soon get a gut instinct of which stone you should buy. You may also ask the Lord & Lady to guide you with this. Let the stone "speak" to you and you will know which one is right for what you want to use it for. This may take a little practice but in time you will be able to do it. There has always been that sense of... "I have to have THIS one" when it has come to me choosing a stone. Rule of thumb, if it feels right to you, it probably is, and if it does not, then it probably isn't. Our inner self usually knows what is right. Let it guide you when choosing a stone. Bless be.