While a universally accepted grading system is used for knowing the value of diamonds, no other system so far are used for colored stones. The Gemological Institute of America (GIA) has developed a grading system for diamonds in the early 1950s but historically, all gemstones were graded using the unaided eye. The GIA system though, included a major innovation-the introduction of 10x magnification as the standard for grading clarity. Assuming the jeweler has perfect vision, other gemstones are still graded using simple examination. For the past several hundred years, gemstones have been broken down into two categories. Some are classified under the precious type and others are categorized as semi-precious. They make for great centerpieces in colored stone jewelry. Though today we think primarily of diamond, ruby, sapphire and emerald as "precious", these categories are based mainly on fashion demands and the composition of these two lists have constantly evolved over time.