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Ruby

A naturally occurring ruby crystal
General
Category Mineral variety
Chemical formula aluminium oxide with chromium, Al2O3:Cr
Identification
Color Red, may be brownish, purplish or pinkish
Crystal habit Varies with locality. Terminated tabular hexagonal prisms.
Crystal system Trigonal (Hexagonal Scalenohedral) Symbol (-3 2/m) Space Group: R-3c
Cleavage No true cleavage
Fracture Uneven or conchoidal
Mohs scale hardness 9.0
Luster Vitreous
Streak white
Diaphaneity transparent
Specific gravity 4.0
Refractive index nω=1.768 - 1.772 nε=1.760 - 1.763, Birefringence 0.008
Pleochroism Orangey red, purplish red
Ultraviolet fluorescence red under longwave
Melting point 2044 °C
Solubility none
Major varieties
Sapphire Any color except red
Corundum various colors
Emery Granular
Crystal structure of ruby

A ruby is a pink to blood-red 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. The ruby is considered one of the four precious stones, together with the sapphire, the emerald, and the diamond.[1]

Prices of rubies are primarily determined by color. The brightest and most valuable "red" called pigeon blood-red, commands a huge 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 (size) also determine the price.

Contents

Physical properties

Rubies have a hardness of 9.0 on the Mohs scale of mineral hardness. Among the natural gems only moissanite and diamond are harder, with diamond having a Mohs hardness of 10.0 and moissonite falling somewhere in between corundum (ruby) and diamond in hardness. Ruby is α-alumina (the most stable form of Al2O3) in which a small fraction of the aluminum3+ ions are replaced by chromium3+ ions. Each Cr3+ is surrounded octahedrally by six O2- ions. This crystallographic arrangement strongly affects each Cr3+, resulting in light absorption in the yellow-green region of the spectrum and thus in the red color of the gem. When yellow-green light is absorbed by Cr3+, it is re-emitted as red luminescence.[2] This red emission adds to the red colour perceived by the subtraction of green and violet light from white light, and adds luster to the gem's appearance. When the optical arrangement is such that the emission is stimulated by 694-nanometer photons reflecting back and forth between two mirrors, the emission grows strongly in intensity. This effect was used by Theodore Maiman in 1960 to make the first successful laser, based on ruby.

All natural rubies have imperfections in them, including color impurities and inclusions of rutile needles known as "silk". Gemologists use these needle inclusions found in natural rubies to distinguish them from synthetics, simulants, or substitutes. Usually the rough stone is heated before cutting. Almost all rubies today are treated in some form, with heat treatment being the most common practice. However, rubies that are completely untreated but still of excellent quality command a large premium.

Some rubies show a 3-point or 6-point asterism or "star". These rubies are cut into cabochons to display the effect properly. Asterisms are best visible with a single-light source, and move across the stone as the light moves or the stone is rotated. Such effects occur when light is reflected off the "silk" (the structurally oriented rutile needle inclusions) in a certain way. This is one example where inclusions increase the value of a gemstone. Furthermore, rubies can show color changes — though this occurs very rarely —; as well as chatoyancy or the "cat's eye" effect.

Natural occurrence

The Mogok Valley in Upper Myanmar (Burma) was for centuries the world's main source for rubies. That region has produced some of the finest rubies ever mined, but in recent years very few good rubies have been found there. The very best color in Myanmar rubies is sometimes described as "pigeon's blood." 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.

Rubies have historically been mined in Thailand, the Pailin and Samlout District of Cambodia, and in Afghanistan. Rubies have rarely been found in Sri Lanka, where pink sapphires are more common. After the Second World War ruby deposits were found in Tanzania, Madagascar, Vietnam, Nepal, Tajikistan, and Pakistan. A few rubies have been found in the U.S. states of Montana, North Carolina, and South Carolina. More recently, large ruby deposits have been found under the receding ice shelf of Greenland. In 2002 rubies were found in the Waseges River area of Kenya.

Spinel, another red gemstone, is sometimes found along with rubies in the same gem gravel or marble. Red spinel may be mistaken for ruby by those lacking experience with gems. However, the finest red spinels can have a value approaching that of the average ruby.[3]

A cut ruby.

Factors affecting value

Diamonds are graded using criteria that have become known as the four Cs, namely color, cut, clarity and carat weight. Similarly natural rubies can be evaluated using the four Cs together with their size and geographic origin.

Color: In the evaluation of colored gemstones, color is the single most important factor. Color divides into three components; hue, saturation and tone. Hue refers to "color" as we normally use the term. Transparent gemstones occur in the following hues: red, orange, yellow, green, blue, violet, purple and pink are the spectral hues. The first six are known as spectral hues; the last two are modified spectral hues. Purple is a hue that falls halfway between red and blue and pink is a paler shade of red.[4] In nature there are rarely pure hues so when speaking of the hue of a gemstone we speak of primary and secondary and sometimes tertiary hues. In ruby the primary hue must be red. All other hues of the gem species corundum are called sapphire. Ruby may exhibit a range of secondary hues. Orange, purple, violet and pink are possible.

The finest ruby is best described as being a vivid medium-dark toned red. Secondary hues add an additional complication. Pink, orange, and purple are the normal secondary hues in ruby. Of the three, purple is preferred because, firstly, the purple reinforces the red making it appear richer.[4] Secondly, purple occupies a position on the color wheel halfway between red and blue. In Burma where the term pigeon blood originated, rubies are set in pure gold. Pure gold is, itself a highly saturated yellow. Set a purplish-red ruby in yellow and the yellow neutralizes its complement blue leaving the stone appearing to be pure red in the setting.[5]

Treatments and enhancements

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.

Improvements used include color alteration, improving transparency by dissolving rutile inclusions, healing of fractures (cracks) or even completely filling them.

The most common treatment is the application of heat. Most, if not all, rubies at the lower end of the market are heat treated on the rough stones to improve color, remove purple tinge, blue patches and silk. These heat treatments typically occur around temperatures of 1800 °C (3300 °F).[6] Some rubies undergo a process of low tube heat, when the stone is heated over charcoal of a temperature of about 1300 °C (2400 °F) for 20 to 30 minutes. The silk is only partially broken as the color is improved.

A less acceptable treatment, which has gained notoriety in recent years, is lead glass filling. Filling the fractures inside the ruby with lead glass dramatically improves the transparency of the stone, making previously unsuitable rubies fit for applications in jewelry. The process is done in four steps:

  1. The rough stones are pre-polished to eradicate all surface impurities that may affect the process
  2. The rough is cleaned with hydrogen fluoride
  3. The first heating process during which no fillers are added. The heating process eradicates impurities inside the fractures. Although this can be done at temperatures up to 1400 °C (2500 °F) it most likely occurs at a temperature of around 900 °C (1600 °F) since the rutile silk is still intact
  4. The second heating process in an electrical oven with different chemical additives. Different solutions and mixes have shown to be successful, however mostly lead-containing glass-powder is used at present. The ruby is dipped into oils, then covered with powder, embedded on a tile and placed in the oven where it is heated at around 900 °C (1600 °F) for one hour in an oxidizing atmosphere. The orange colored powder transforms upon heating into a transparent to yellow-colored paste, which fills all fractures. After cooling the color of the paste is fully transparent and dramatically improves the overall transparency of the ruby.

If a color needs to be added, the glass powder can be "enhanced" with copper or other metal oxides as well as elements such as sodium, calcium, potassium etc.

The second heating process can be repeated three to four times, even applying different mixtures.[7] When jewelry containing rubies is heated (for repairs) it should not be coated with boracic acid or any other substance, as this can etch the surface; it does not have to be "protected" like a diamond.

Synthetic and imitation rubies

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 Frenic and Freil made crystal corundum from which small stones could be cut. Frimy and Auguste Verneuil manufactured artificial ruby by fusing BaF2 and Al2O3 with a little Chromium at red heat. In 1903 Verneuil announced he could produce synthetic rubies on a commercial scale using this flame fusion process.[8]

Other processes in which synthetic rubies can be produced are through the 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 curves, 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 gemmological 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[9] at Hughes Research Laboratories in Malibu, California, beating several research teams including those of Charles H. Townes at Columbia University, Arthur Schawlow at Bell Labs,[10] and Gould at a company called TRG (Technical Research Group). 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. Rubies can also be used in applications where high hardness is required such as material for scanning probe tips in a coordinate measuring machine.

Imitation rubies are also marketed. Red spinels, red garnets, and colored glass have been falsely claimed to be rubies. Imitations go back to Roman times and already in the 17th century techniques were developed to color foil red—by burning scarlet wool in the bottom part of the furnace—which was then placed under the imitation stone.[11] Trade terms such as balas ruby for red spinel and rubellite for red tourmaline can mislead unsuspecting buyers. Such terms are therefore discouraged from use by many gemological associations such as the Laboratory Manual Harmonisation Committee (LMHC).

Records

The Smithsonian's National Museum of Natural History in Washington DC, has received one of the world's largest and finest ruby gemstones. The 23.1 carats (4.6 g) Burmese ruby, set in a platinum ring with diamonds, was donated by businessman and philanthropist Peter Buck in memory of his wife Carmen Lúcia. This gemstone displays a richly saturated red color combined with an exceptional transparency. The finely proportioned cut provides vivid red reflections. The stone was mined from the Mogok region of Burma (now Myanmar) in the 1930s.[12]

Synthetic ruby is also used extensively in the metrology field, serving as stylus material for contact measuring instruments such as a Coordinate Measuring Machine (CMM).

Historical and cultural references

  • An early recorded note of the transport and trading of rubies arises in the literature on the North Silk Road of China, where in about 200 BC rubies were carried along this ancient trackway moving westward from China.[13]
  • Rubies have always been held in high esteem in Asian countries. They were used to ornament armor, scabbards, and harnesses of noblemen in India and China. Rubies were laid beneath the foundation of buildings to secure good fortune to the structure.[14]

See also

References

  1. ^ Precious Stones, Max Bauer, p 2
  2. ^ "Ruby: causes of color". http://www.webexhibits.org/causesofcolor/6AA.html. Retrieved 15 may 2009. 
  3. ^ Wenk, Hans-Rudolf; Bulakh, A. G. (2004). Minerals: their constitution and origin. Cambridge, U.K.: Cambridge University Press. pp. 539–541. ISBN 0-521-52958-1. 
  4. ^ a b Wise, Richard W. (2006). Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones. Brunswick House Press. pp. 18–22. ISBN 0972822380. 
  5. ^ GemWise: What Color is Pigeon's Blood
  6. ^ "The Heat Treatment of Ruby and Sapphire". Bangkok, Thailand: Gemlab Inc.. 1992. 
  7. ^ Milisenda, C C (2005). "Rubine mit bleihaltigen Glasern gefullt" (in German). Zeitschrift der Deutschen Gemmologischen Gesellschaft (Deutschen Gemmologischen Gesellschaft) 54 (1): 35–41. 
  8. ^ "Bahadur: a Handbook of Precious Stones". 1943. http://www.farlang.com/gemstones/bahadur_handbook_of_precious_stones/page_067. Retrieved 2007-08-19. 
  9. ^ Maiman, T.H. (1960). "Stimulated optical radiation in ruby". Nature 187 (4736): 493–494. doi:10.1038/187493a0. 
  10. ^ Hecht, Jeff (2005). Beam: The Race to Make the Laser. Oxford University Press. ISBN 0-19-514210-1. 
  11. ^ "Thomas Nicols: A Lapidary or History of Gemstones". 1652. http://www.farlang.com/gemstones/nicols-history-gemstones/page_036. Retrieved 2007-08-19. 
  12. ^ "The Carmen Lúcia Ruby". Exhibitions. http://www.mnh.si.edu/exhibits/ruby/index.htm. Retrieved 2008-02-28. 
  13. ^ C.Michael Hogan,Silk Road, North China, The Megalithic Portal, ed. A. Burnham
  14. ^ Smith, Henry G. (1896). "Chapter 2, Sapphires, Rubies". Gems and Precious Stones. Charles Potter Government Printer, Australia. http://www.farlang.com/gemstones/smith-gems-prec-stones/page_028. 

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

RUBY (Lat. rubeus, red), the most valued of all gem-stones, a red transparent variety of corundum, or crystallized alumina. It is sometimes termed "oriental ruby" to distinguish it from the spinel ruby, which is a stone of inferior hardness, density and value (see Spinel). When the word ruby is used without any qualifying prefix, it is always the true or so-called oriental stone that is meant in modern nomenclature. Ancient writers, relying chiefly on colour, classed together under a common name several brilliant red stones, such as the ruby, spinel and garnet: thus the etvOpa of Theophrastus and the Carbunculus of Pliny were names which seem to have been applied to several distinct minerals. Although the word ruby is used in the English translation of the Old Testament it is improbable that the true ruby was known to the ancient Hebrews.

The ruby crystallizes in the hexagonal system (see Corundum). The crystals have no true cleavage, but tend to break along certain gliding planes. The colour of ruby varies from deep cochineal to pale rose-red, in some cases with a tinge of purple, the most valued tint being that called by experts pigeon's-blood colour. On exposure to a high temperature, the ruby becomes green, but regains its original colour on cooling. The red colour of ruby may be due to chromium. When a ruby of the most esteemed tint is examined with the dichroscope, one image is generally seen to be carmine and the other aurora-red, the red colour inclining to orange. This test serves to distinguish the true ruby from spinel and from garnet, since these minerals, being cubic, are not dichroic. Another means of distinction is afforded by the specific gravity of ruby (about 4), which is higher than that of spinel and garnet, whilst the superior hardness of the ruby (about 9) furnishes yet another test. The high refractivity of ruby is also characteristic, the mean ordinary index being 1.77 and the extraordinary 1.76. When cut and polished the ruby is therefore a brilliant stone, but having weak dispersive power it lacks fire. Subjected to radiant discharge in a Crookes tube, the ruby, like other forms of corundum, phosphoresces with a vivid red glow.

The oriental ruby is a mineral of very limited distribution. Its most famous localities are in Upper Burma, but until the British annexation of the country in 1886 the mines were so jealously guarded that little was known as to the conditions under which the mineral occurred. Soon after the annexation, the ruby districts were officially visited, and reported on, by Mr C. Barrington Brown, and specimens from the mines were exhaustively studied by Professor J. W. Judd. The principal district is situated in the neighbourhood of Mogok, 90 m. N.N.E. of Mandalay. The ruby occurs in bands of a crystalline limestone, associated with granitic and gneissose rocks, some of which are highly basic; and it is from the anorthite, or lime-felspar, and the associated minerals in the pyroxenegneisses, that the corundum, spinel and calcite, may, according to Judd, have been derived. Probably the felspar is first altered to scapolite, and this on decomposition would yield calcium carbonate and hydrous aluminium silicates, from which the anhydrous alumina might ultimately be separated. The limestone contains (in addition to the ruby) spinel, garnet, graphite, wollastonite, scapolite, felspar, mica, pyrrhotite and other minerals. The ruby, like other kinds of corundum, suffers alteration under certain conditions, and passes by hydration into gibbsite and diaspore, which by further alteration and union with silica, &c., may yield margarite, vermiculite, chlorite and other hydrous silicates.

The Burmese rubies are not generally worked in the limestone matrix, ! but are mostly found loose in detrital matter, which is clayey and sandy in character and yellowish-brown in colour, and is known locally as "byon." Some of the deposits occur in limestone caverns, where they may, like cave-earth, represent the insoluble residue of the limestone. Workings in the cave-deposits are called "loodwins" (crooked mines). In the alluvium of the valleys, the ruby-pits are known as "twinlones" (round pits), whilst workings in the rubyearth on the hillsides are termed "hmyaudwins" (water mines). The byon contains, with the ruby, other coloured corundums and spinels. Burmese rubies are found also in crystalline limestone in the hills near Sagyin, about 20 m. N. of Mandalay, and it is of mineralogical interest to note that the limestone here contains chondrodite.

Rubies are found in Siam, at several localities in the provinces of Chantabun and Krat; and Professor H. Louis has described their occurrence at Moung Klung in this region. The rubies are found with sapphires and spinels, in gravels, resting in some cases on basic igneous rocks. The Siam rubies are generally of dark colour, often inclining to a deep reddish brown. Rubies occur, with sapphires and other minerals, in the gem-gravels of Ceylon, but are not usually of such good colour as the Burmese stones. A cloudy variety, which, when cut with a convex surface, exhibits a luminous star, is known as star-ruby '(see' Asterias). In peninsular India rubies are rarely found, though they have been reported from the corundum deposits of Madras and Mysore. The ruby is known, however, to occur in a micaceous limestone at Jagdalak, near Kabul in Afghanistan.

Rubies, generally of pale colour, are found with the sapphires of Montana, especially at Yogo Gulch near Utica. In the corundum deposits of N. Carolina ruby is occasionally met with, especially at Cowee Creek, Macon (disambiguation)|Macon county, where it occurs in crystals of tabular, rhombohedral and prismatic habit. These crystals, sometimes of fine colour, are found in gravels resting on a soft rock called saprolite, which results from the weathering of certain basic igneous rocks; and it is notable that the ruby crystals are associated with the variety of garnet termed rhodolite, as described by Professor Judd and W. E. Hidden. Australia has occasionally yielded rubies, but mostly of small size and inferior quality. In New South Wales and in Victoria they have been found in drift gravels, and a magentacoloured turbid variety from Victoria has been described under the name of barklyite.

Rubies have been produced artificially with much success. At one time it was the practice to fuse together small fragments of the natural stone; and gems cut from such material were known as reconstructed rubies. This process has given way to Professor A. Verneuil's method of forming artificial ruby from purified ammonia-alum with a certain proportion of chromealum. The finely powdered material is caused to fall periodically into an oxyhydrogen flame, the heat of which decomposes the alum, and the alumina thus set free forms liquid drops which collect and solidify as a pear-shaped mass. When of the characteristic pigeon's-blood colour, the synthetical ruby contains about 2.5% of chromic oxide. The manufactured ruby possesses the physical characters of corundum, but may generally be distinguished by microscopic bubbles and striae. -The manufacture is carried out commercially. (For other processes, see GEM, Artificial.) It should be noted that several minerals known popularly as rubies have no relation to the true red corundum. Thus; "Cape rubies" from the South African diamond mines, "Australian rubies" from South Australia, and "Arizona rubies" are merely fine garnets; "Siberian ruby" is red tourmaline (see Rubellite), and "Balas ruby" is spinel (q.v.). Ruby silver is a name applied to light red silver ore, or proustite; ruby copper is merely cuprite, in brilliant crystals; and ruby-blende is a clear red variety of zinc sulphide.

BIBLIOGRAPHY. -For the Burma ruby, see "The Rubies of Burma and Associated Minerals: their mode of occurrence, origin and metamorphoses, by C. Barrington Brown and Professor J. W. Judd, Phil. Trans., 1897, 187, p. 151. For the ruby of Siam, see The Ruby and Sapphire Deposits of Moung Klung, Siam," by H. Louis, Mineralog. Mag., 1894, to, p. 267. For synthetical ruby, see G. F. Herbert Smith, Mineralog. Mag., 1908, 15, p. 153; and J. Boyer, La Synthese des pierres precieuses (Paris, 1909). (F. W. R.*)


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Wiktionary

Up to date as of January 14, 2010

Definition from Wiktionary, a free dictionary

See also ruby

Contents

English

Proper noun

Singular
Ruby

Plural
-

Ruby

  1. A female given name.
    • 1992 Karen Kijewski, Kat's Cradle, page 76:
      And those are her two daughters, Opal and Ruby. Her husband, Joshua, named them. He said they were to be the jewels of his old age. She would never have thought of names like that. There wasn't an ounce of sentiment in her body.
  2. (computing, programming languages) A dynamic, reflective, general-purpose object-oriented programming language developed in the 1990s.

See also

Translations

Noun

Singular
Ruby

Plural

Ruby

  1. (Cockney rhyming slang) A curry, short for Ruby Murray.
    We're going down the Indian for a Ruby - wanna join us?

Anagrams

  • Anagrams of bruy
  • bury

Wikibooks

Up to date as of January 23, 2010
(Redirected to Ruby Programming article)

From Wikibooks, the open-content textbooks collection

Ruby was named after the precious gem.

Ruby is an interpreted, object-oriented scripting language. Its creator, Yukihiro Matsumoto, a.k.a "Matz", released it to the public in 1995.

The book is currently broken down into several sections, and is intended to be read sequentially. Getting started will show how to install and get started with Ruby in your environment. Basic Ruby demonstrates the main features of the language syntax. The final section, Intermediate Ruby covers a selection of slightly more advanced topics. Each section is designed to be self contained. Finally, the Ruby language section is organized like a reference to the language.

Contents

Table of Contents

Wikibook Development Stages
Sparse text 00%.svg Developing text 25%.svg Maturing text 50%.svg Developed text 75%.svg Comprehensive text: 100%.svg

Getting started

Overview
Installing Ruby
Ruby editors
Notation conventions
Interactive Ruby
Mailing List FAQ

Basic Ruby

Hello world
Strings
Alternate quotes
Here documents
ASCII
Introduction to objects
Ruby basics
Data types -- numbers, strings, hashes and arrays
Writing methods
Classes and objects
Exceptions

Intermediate Ruby

Unit testing
RubyDoc
Rake

Ruby reference

Modules

External links

Learning Ruby

Books

Quick Reference


Bible wiki

Up to date as of January 23, 2010

From BibleWiki


(Heb. peninim), only in plural (Lam. 4:7). The ruby was one of the stones in the high priest's breastplate (Ex. 28:17). A comparison is made between the value of wisdom and rubies (Job 28:18; Prov. 3:15; 8:11). The price of a virtuous woman is said to be "far above rubies" (Prov. 31:10). The exact meaning of the Hebrew word is uncertain. Some render it "red coral;" others, "pearl" or "mother-of-pearl."

This entry includes text from Easton's Bible Dictionary, 1897.

what mentions this? (please help by turning references to this page into wiki links)


Simple English

Ruby is a type of precious stone. It is often associated with emerald, sapphire and topaz. It is usually red, but can sometimes be other colors.

bjn:Mirah delima








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