Despite the immense popularity of diamonds, colored gemstones have always been among the most popular and expressive forms of jewelry. Long before diamonds were used in jewelry, people valued sapphires, rubies, emeralds, and all other colored stones. The precious gemstones - sapphire, ruby, and emerald - are among the most prized. Precious gemstones of good size and quality are so rare that a natural, unenhanced, strongly colored stone can be worth as much per carat, or more, than a diamond of comparable quality.

Given the extreme cost and rarity of such stones, jewelers developed ways to enhance the appearance of more common stones, both precious and semi-precious. For hundreds of years, it has been common practice to heat gems to bring out their best color. There are many other common types of treatment to enhance the beauty of colored gemstones. Emeralds are often oiled and waxed to protect them and to hide fine lines that naturally occur in the stone. Some sapphires have their blue color enhanced using diffusion, a chemical process. Certain stones are treated with radiation.. All these practices are standard in the jewelry industry; in fact, enhancement is so common that good quality unenhanced stones often come with a certificate stating that fact. Other than the oil on emeralds, which can last for years before needing replacement, any quality enhancement is permanent and should not require special care. Bringing your emerald in for a cleaning and re-oiling on a regular basis will help keep it looking its best.

Synthetic or "lab-created" stones, on the other hand, are grown using the same ingredients as the natural stones. They are chemically identical to natural stones, but cost much less. Lab-created gems frequently have fewer "inclusions," the internal flaws common in precious gems. With technical advances, many high quality lab-created stones can only be differentiated from a natural by a trained professional. Almost any gem can be made in a lab, but the precious gems - emeralds, rubies and sapphires - are the most common.