When buying a gemstone - buy the best quality, most experts recommend. Choose a smaller stone of higher quality over a larger stone of lower quality, or buy a higher quality gem from an unusual variety if your budget is too small. You may be surprised how beautiful and affordable garnets, tourmalines, tanzanites, and other exotic gemstones can be.
Color is the key factor.
A common misperception in judging gems is people assume that the darker the color, the better the stone. If a gem's color is too dark, it is subdued and lifeless. A much better rule of thumb is the brighter and more rich and vivid the color the better. In general, within each gemstone variety, a clear, medium-tone, very intense and saturated primary color is the most preferred. Muted colors or colors between hues, which you might find very attractive, are usually less expensive.