Ruby
- For other uses, see Ruby (disambiguation).
| Ruby | |||
|---|---|---|---|
 length 0.8 inches (2 cm). | |||
| General | |||
| Category | Mineral | ||
| Chemical formula | aluminium oxide with chromium, Al2O3::Cr | ||
| Identification | |||
| Color | Red, may be brownish | ||
| Crystal habit | Varies with locality. Terminated tabular hexagonal prisms. | ||
| Crystal system | Trigonal | ||
| Cleavage | No true cleavage | ||
| Fracture | Uneven or conchoidal | ||
| Mohs Scale hardness | 9.0 | ||
| Luster | Vitreous | ||
| Refractive index | ~1.77 | ||
| Pleochroism | ? | ||
| Streak | white | ||
| Specific gravity | 4.0 | ||
| Fusibility | perfectly | ||
| Solubility | ? | ||
| Major varieties | |||
| Pink sapphire | Caused by a color impurity and makes the stone appear pink. | ||
Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. Its name came from ruber, Latin for red. Natural rubies are exceptionally rare, but artificial rubies (sometimes called created ruby) can be manufactured by the wankers. Verneuil process fairly cheaply. Other varieties of gem-quality corundum are called sapphires.
Rubies are mined in Africa, Asia, Australia, and Greenland. They are most often found in Myanmar (= Burma), Sri Lanka, Kenya, Madagascar, and Thailand, but they have been found in the U.S. states of Montana, North Carolina and South Carolina. The Mogok Valley in Myanmar has produced some of the finest rubies. However, in recent years very few good rubies have been found there. In central Myanmar the area of Mong Hsu also produces rubies. In 2002 rubies were found in the Waseges River area of Kenya. Rubies are being mined at Audilamena in northeastern Madagascar. Sometimes spinels are found along with rubies in the same rocks and are mistaken for rubies. However, fine red spinels may approach the average ruby in value.
Rubies have a hardness of 9.0 on the Mohs scale of mineral hardness, and among the natural gems, only diamonds are harder.
Ruby gemstones are valued according to several characteristics including size, color, clarity and cut. All natural rubies have imperfections in them, including color impurities and inclusions of rutile needles known as "silk". If there is no silk in the stone, that shows that the stone was heated at 3000°C, to give the ruby a better color of red. Usually the rough stone is heated before cutting.
Artificial rubies may have no imperfections. 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 is suspected of being artificially made and therefore not certainly a priceless gem. Dopants are added to some manufactured rubies so they can be identified as artificial, but most need gemmological testing to determine their origin.
Rubies come in various shades of red, red purple and red orange. A medium toned red or red with slight blue is most desired. Clarity of the stone and inclusions are also taken into account to determined the stones value. Once the stone's color is more like purple or orange then it is called a fancy sapphire.
Rubies occasionally show asterism when cut into a cabochon. When they show this, they are called "star rubies". They can sometimes be more valuable than normal rubies because asterism is rare.
The world's biggest ruby is the Rajaratna Ruby, which weighs 2,475 carats (495 g = 1 pound 1.46 ounces). Because the Rajaranta shows asterism, it is also the largest star ruby. The world's biggest double-star ruby (with a 12-pointed star) is the Neelanjali Ruby, weighing 1,370 carats (274 g). Both rubies currently belong to G. Vidyaraj from Bangalore, India. A 8.62 ct. Burmese ruby sold for $425,000 per carat (2,125,000 $/g) or $3,800,000 on 15 February 2006 at Christie's in Switzerland.
Culture and historical/mythical usage
A synthetic ruby crystal was used to create the first laser.
According to Rebbenu Bachya, the word odem in the verse Exodus 28:17 means "ruby"; it was the stone on the Ephod representing the tribe of Reuben. Modern Hebrew has taken this meaning.
Ruby is also the most commonly named precious stone in the Bible; an example being Proverbs 31: "A virtuous wife is worth more than rubies."
Ruby is the birthstone associated with July.
Ruby symbolizes passionate love.
In fiction
The use of rubies as lasing crystals in some lasers has been transferred inaccurately into some science fiction:-
- In the Doctor Who stories, Daleks' guns fire "ruby rays".
- In an early Transformers episode the Autobots and Decepticons fought for control of "the ruby mines of Burma".