Many will say that colored gemstones are the Cinderella of the world of jewels. Diamonds get the most attention - but colored gemstones are fascinating and beautiful and some are even more rare than diamonds. Although we've come to think of white diamonds as "traditional" for engagement ring stones, many will remember that Princess Diana's engagement ring was a very large oval blue sapphire, surrounded by smaller white diamonds. It was different and memorable.

When people talk about "jewel tones," they referring to the panoply of colors found in precious and semiprecious colored gemstones: ruby, sapphire, topaz and jade, to name a few. Gemstones, both precious and semiprecious, are minerals which, when cut and polished, are used to make beautiful jewelry. Certain non-minerals, such as lapis lazuli, amber and jet, are also lumped together with mineral gemstones. The term "precious" and "semiprecious" is confusing, as there is no set list for the classifications and they depend more on popularity. With a reputation that continues to exceed that of other stones, diamonds, rubies, sapphires, and emeralds are firmly in the "precious" classification; as are pearls - although they aren't technically stones, their popularity in jewelry guarantees their place as a precious gem.

Unlike diamonds, there is no grading system for gemstones, although the GIA grading for diamonds can be modified and applied to some gemstones. In white diamonds, the fire of the finished piece is determined by the cut; uncut diamonds do not have the sparkle characteristic of a cut diamond. Therefore, in white diamonds, the cut is the most important determining factor in the quality of a stone, followed by clarity and color. In gemstones that have color, including colored diamonds, the purity and beauty of the color determines the value. Therefore, color is the primary factor in the value of a colored gemstone, followed by clarity to a lesser extent (emeralds and rubies with few inclusions are very rare) and cut. Unlike white diamonds, colored gemstones with optical phenomena within the stone (such as star effects seen in star sapphires) make the gemstone more valuable.

All of this makes purchasing colored gemstones more confusing even than buying white diamonds. How much should you expect to pay for a 1-carat ruby, for example? It will depend on the quality of the color and the cut, but you won't have the standardized grading system to go by.

If you are in the market for colored gemstones because of they are relatively inexpensive, unusual and beautiful, you will need to do more comparative shopping and spend a lot of time looking before you make a purchase.