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A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires. Ruby is one of the traditional cardinal gems, alongside amethyst, sapphire, emerald, and diamond.[3] The word ruby comes from ruber, Latin for red. The color of a ruby is due to the element chromium.


The quality of a ruby is determined by its color, cut, and clarity, which, along with carat weight, affect its value. The brightest and most valuable shade of 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. Ruby is the traditional birthstone for July and is usually pinker than garnet, although some rhodolite garnets have a similar pinkish hue to most rubies. The world's most valuable ruby to be sold at auction is the Sunrise Ruby.

If one percent of the aluminium ions are replaced by chromium in ruby, the yellow-green absorption results in a red color for the gem.[5] Additionally, absorption at any of the above wavelengths stimulates fluorescent emission of 694-nanometer-wavelength red light, which adds to its red color and perceived luster.[6] The chromium concentration in artificial rubies can be adjusted (in the crystal growth process) to be ten to twenty times less than in the natural gemstones. Theodore Maiman says that "because of the low chromium level in these crystals they display a lighter red color than gemstone ruby and are referred to as pink ruby."[7]

After absorbing short-wavelength light, there is a short interval of time when the crystal lattice of ruby is in an excited state before fluorescence occurs. If 694-nanometer photons pass through the crystal during that time, they can stimulate more fluorescent photons to be emitted in-phase with them, thus strengthening the intensity of that red light. By arranging mirrors or other means to pass emitted light repeatedly through the crystal, a ruby laser in this way produces a very high intensity of coherent red light.

Generally, gemstone-quality corundum in all shades of red, including pink, are called rubies.[8][9] However, in the United States, a minimum color saturation must be met to be called a ruby; otherwise, the stone will be called a pink sapphire.[8] Drawing a distinction between rubies and pink sapphires is relatively new, having arisen sometime in the 20th century. Often, the distinction between ruby and pink sapphire is not clear and can be debated. As a result of the difficulty and subjectiveness of such distinctions, trade organizations such as the International Colored Gemstone Association (ICGA) have adopted the broader definition for ruby which encompasses its lighter shades, including pink.

Historically, rubies have been mined in Thailand, in the Pailin and Samlout District of Cambodia, as well as in Afghanistan, Australia, Brazil, Colombia, India, Namibia, Japan, and Scotland. After the Second World War, ruby deposits were found in Madagascar, Mozambique, Nepal, Pakistan, Tajikistan, Tanzania, and Vietnam.[10]

Spinel, another red gemstone, is sometimes found along with rubies in the same gem gravel or marble. Red spinels may be mistaken for rubies by those lacking experience with gems. However, the finest red spinels, now heavily sought, can have values approaching all but the finest examples of ruby.[11][12] In Afghanistan, rubies are mined at Jegdalek.

The Mogok Valley in Upper Myanmar (Burma) was for centuries the world's main source for rubies. That region has produced some exceptional rubies, however in recent years few good rubies have been found. In central Myanmar, the area of Mong Hsu began producing rubies during the 1990s and rapidly became the world's main ruby mining area. The most recently found ruby deposit in Myanmar is in Namya (Namyazeik) located in the northern state of Kachin.[13]

Improving the quality of gemstones by treating them is common practice. Some treatments are used in almost all cases and are therefore considered acceptable. During the late 1990s, a large supply of low-cost materials caused a sudden surge in supply of heat-treated rubies, leading to a downward pressure on ruby prices.

Another treatment, which has become more frequent in recent years, is lead glass filling. Filling the fractures inside the ruby with lead glass (or a similar material) dramatically improves the transparency of the stone, making previously unsuitable rubies fit for applications in jewelry.[22] The process is done in four steps:

In 1837, Gaudin made the first synthetic rubies by fusing potash alum at a high temperature with a little chromium as a pigment. In 1847, Ebelmen made white sapphire by fusing alumina in boric acid. In 1877, Edmond Frémy and industrial glass-maker Charles Feil made crystal corundum from which small stones could be cut. In 1887, Fremy and Auguste Verneuil manufactured artificial ruby by fusing BaF2 and Al2O3 with a little chromium at red heat.

Other processes in which synthetic rubies can be produced are through Czochralski's pulling process, flux process, and the hydrothermal process. Most synthetic rubies originate from flame fusion, due to the low costs involved. Synthetic rubies may have no imperfections visible to the naked eye but magnification may reveal curved striae and gas bubbles. The fewer the number and the less obvious the imperfections, the more valuable the ruby is; unless there are no imperfections (i.e., a perfect ruby), in which case it will be suspected of being artificial. Dopants are added to some manufactured rubies so they can be identified as synthetic, but most need gemological testing to determine their origin.

Synthetic rubies have technological uses as well as gemological ones. Rods of synthetic ruby are used to make ruby lasers and masers. The first working laser was made by Theodore H. Maiman in 1960.[27] Maiman used a solid-state light-pumped synthetic ruby to produce red laser light at a wavelength of 694 nanometers (nm). Ruby lasers are still in use.

The concept of electromagnetic radiation amplification through the mechanism of stimulated emission had already been successfully demonstrated in the laboratory by way of the maser, using other materials such as ammonia and, later, ruby, but the ruby laser was the first device to work at optical (694.3 nm) wavelengths. Maiman's prototype laser is still in working order.

If the new Ruby version is from a different stable branch, then please use a new target directory for installation.That is to say, a previous RubyInstaller-3.0.x installation should not be updated by installing RubyInstaller-3.1.x into the same directory.This is because gems with C extensions are not compatible between ruby-3.0 and 3.1.Find out more in the FAQ.

A special thanks to Mike Clark and Ara Howard for inspiring this project. Mike Clark wrote an excellent blog post about learning Ruby through unit testing. This sparked an idea that has taken a bit to solidify, that of bringing new rubyists into the community through testing. Ara Howard then gave us the idea for the Koans in his ruby quiz entry on Meta Koans (a must for any rubyist wanting to improve their skills). Also, "The Little Lisper" taught us all the value of the short questions/simple answers style of learning.

A: In-stock orders can be cancelled with no additional charge as long as the order has not been shipped. Custom and special orders must be cancelled within 24 hours of placing the order online. To cancel an in stock order, please send an email to and include your name and order confirmation number.

In constructors, avoid unnecessary disjunctive assignment (=) of instance variables.Prefer plain assignment.In ruby, instance variables (beginning with an @) are nil until assigned a value, so in most cases the disjunction is unnecessary.

RVM lets you deploy each project with its own completely self-contained and dedicated environment, from the specific version of ruby, all the way down to the precise set of required gems to run your application. Having a precise set of gems also avoids the issue of version conflicts between projects, which can cause difficult-to-trace errors and hours of hair loss. With RVM, NO OTHER GEMS than those required are installed. This makes working with multiple complex applications, where each has a long list of gem dependencies, much more efficient. RVM lets you easily test gem upgrades, by switching to a new clean set of gems to test with, while leaving your original set intact. It is flexible enough to even let you maintain a set of gems per environment, or per development branch, or even per individual developer's taste!

RVM reduces the complexity of the many facets of ruby development through its command-line API. With RVM, you can have **identical** self-contained environments in your Development, CI, Q/A, Staging, and Production environments. No more hidden gotchas: if it works for one of them, it will work in all of them. With named gemsets, you can reliably and immediately push changes from one environment to another. And, RVM is for Ruby applications, *not just for Rails*! Any Ruby based application will benefit from your use of RVM.

RVM enables you to easily test both upgrade and escape paths very easily and consistently. With RVM, you can run a test suite, rake tasks, benchmarks and gem commands against multiple ruby versions at the same time. This means that you can easily ensure your applications work in Ruby 1.8.X, REE, MRI 1.9.1, jruby, etc... and quickly expose any areas in which they do not.

RVM helps ensure that all aspects of Ruby are completely contained within user space, strongly encouraging safer, non-root use. Use of RVM rubies thus provides a higher level of system security, and therefore reduces risk and cuts overall system downtime. Additionally, since all processes run at the user level, a compromised ruby process cannot compromise the entire system.

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