1 Hardness: cubic zirconia has a rating of approximately 8 on Mohs hardness scale vs. a rating of 10 for diamond. 2  Specific gravity: the density of cubic zirconia is about 1.7 times that of diamond. 3  Refractive index: cubic zirconia has a refractive index of 2.15â2.18, compared to a diamond's 2.42.he synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO 4).
When GPS service was first made available for civilians in 1983, for national security reasons, the U.S. military decided to scramble the signal, making it a little too inaccurate to be reliable. This practice, also known as selective availability, was aimed at preventing military use of GPS by the enemies.
Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. Garmin GPS receivers are accurate to within 15 meters, on average. Newer Garmin GPS receivers with WAAS (Wide Area Augmentation System) capability can improve accuracy to less than 3 meters on average.ere are some other interesting facts about the GPS satellites (also called NAVSTAR, the official U.S. Department of Defense name for GPS): 1  The first GPS satellite was launched in 1978. 2  A full constellation of 24 satellites was achieved in 1994. 3  Each satellite is built to last about 10 years.