Ruby on Rails, often shortened to Rails or RoR, is an open source web application framework for the Ruby programming language. Rails gives the web developer the ability to create pages and applications that gather information from the web server, talk to or query the database, and render templates out of the box. As a result, Rails features a routing system that is independent of the web server. (Source WikiPedia)
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| General | |
| Category | Mineral variety |
| Formula (repeating unit) |
aluminium oxide with chromium, Al2O3:Cr |
| Crystal symmetry | (Hexagonal scalenohedral, H-M symbol: (3 2/m), Space group R3c |
| Identification | |
| Color | Near colorless through pink through all shades of red to a deep crimson |
| Crystal habit | Terminated tabular hexagonal prisms. |
| Crystal system | Trigonal |
| Cleavage | No true cleavage |
| Fracture | Conchoidal, splintery |
| Tenacity | Brittle |
| Mohs scale hardness | 9.0 |
| Luster | Subadamantine, vitreous, pearly (on partings) |
| Streak | white |
| Diaphaneity | transparent, translucent |
| Specific gravity | 3.97 – 4.05 |
| Optical properties | Uniaxial - |
| Refractive index | nω=1.768–1.772 nε=1.760–1.763 |
| Birefringence | 0.008 |
| Pleochroism | Strong: purplish-red - orangy-red |
| Dispersion | 0.018 |
| Ultraviolet fluorescence | red under longwave |
| References | |
A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires. Ruby is considered one of the four precious stones, together with sapphire, emerald and diamond.
Prices of rubies are primarily determined by color.The brightest and most valuable "red" called blood-red or "pigeon blood", commands a large premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. Cut and carat (weight) are also an important factor in determining the price. Ruby is the traditional birthstone for July and is always lighter red or pink than garnet. The world's most expensive ruby is the Sunrise Ruby.
