Diamond professionals use the grading system developed by GIA in the 1950s, which established the use of four important factors to describe and classify diamonds: Clarity, Color, Cut, and Carat Weight. These are known as the Four C s. When used together, they describe the quality of a finished diamond.
0. Most Americans adjust their clocks for Daylight Saving Time (DST) once in the spring and once in the fall -- but residents of two states, Hawaii and Arizona, have chosen not to observe it. This clocks stands in a city park in Glendale, Arizona. Wikimedia Commons. Arizona participated for one summer.
The names in each time zone change along with Daylight Saving Time. Eastern Standard Time (EST) becomes Eastern Daylight Time (EDT), and so forth. Arizona, Puerto Rico, Hawaii, U.S. Virgin Islands and American Samoa do not observe Daylight Saving Time. Read more about the new federal law that took effect in March 2007 which extended Daylight Saving Time by four weeks.