Ruby

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Tiffany Ruby Ring.jpg

The name 'ruby' is used for red corundum which is colored by chromium.

Etymology

Ruby comes from the latin word for red: 'ruber'. The medieval Latin adjective 'rubinus' was derived from 'ruber' and eventually started to be used as a noun for red corundum. From there it was a small step from rubinus to ruby.

History

Ancient History

The area around Mogok, Myanmar has seen human habitation since the middle paleolithic period. It is not so hard to believe that these early inhabitants would have stumbled upon the fine rubies of this locality and kept them as decoration, amulets or maybe even tools. Archaeological investigations have been very scarce. The restrictions for foreigners to enter the country that have been put in place by the military regime of Myanmar prevents us from getting a clear picture of the ancient inhabitants of the area and their use of rubies. Another ancient source of gem corundum has been Sri Lanka.


We can find written accounts of red stones that could be ruby in the writings of Theophrastus who speaks of red stones that resemble a hot coal when viewed with the sun behind it. He calls this stone anthrax but whether he was describing garnet, spinel or ruby isn't clear. Pliny's account on red stones is similarly vague and seems to describe more than one red gemstone under the same name; carbunculus. An interesting note is that Pliny mentions glass imitation stones that can be distinguished from genuine gemstones by hardness and inclusion studies.

Middle Ages

After the fall of the Western Roman Empire the epicentre of science moved east a bit. Arabic scholars during the second half of the first millennium AD speak of Yakut, a term used for corundum and a few other gemstones. It is believed that red Yakut is correctly translated to ruby. The writers of Asia Minor had a far better knowledge of ruby localities then the classical writers and when one reads the descriptions known deposits like Badakshan and Sri Lanka can be recognized. One polymath in particular leaves very little doubt that he is describing ruby; the 11th century scholar Al-Biruni, who conducted specific gravity determinations on a whole series of gemstones. His findings are very accurate; he lists a specific gravity of 3.85 for ruby. Two centuries later the Europeans were still fumbling around in the dark. This can be seen in the writings of Albertus Magnus who erroneously mentions Libya as a major locality, a mistake most likely to have come from reading the 11th century lapidary from Marbodus. Rubies from present day Afghanistan, Sri Lanka and Myanmar would have reached Europe through the ports on the eastern shore of the Mediterranean up until then.


When western European armies went on their crusades in the 11th and 12th centuries they encountered (and looted) the riches of the Arabic world. With it came a revived interest in the East and it's economical potential. The travel logs of Marco Polo, written in the 13th century were the first eye-witness accounts of the world to the east of present day India and his memoirs have inspired many to travel to the East and harvest it's riches. The centuries after Polo's journey are the ages of discovery that brought new gemstones to the West along with a better understanding of their nature and origin.


Plique-à-Jour Enamel, Diamond and Red Ruby Grape Cluster Brooch.
Photo Courtesy of Lang Antiques

Renaissance & Enlightenment

The increased contact with the advanced Arabic scholars from the 11th century and later the invention of movable print during the last years of the Middle Ages engendered a new level of knowledge among European readers. Accounts from de Boodt and Nicols - the authors of two lapidaries of the 17th century - discuss rubies, their deposits and their use in greater detail then any of their European predecessors. The 18th century is marked by a further growing mineralogical consciousness until finally ruby and sapphire were both recognized as corundum around 1800.

Modern History

The heat treatment of ruby to improve color and clarity is described in some of the earliest known sources on the subject. The beginning of the 19th century saw the invention of the gas blowpipe which enabled higher temperatures to be reached than had ever been achieved previously. E.D. Clarke published details of his experiments with it:


...two rubies were placed upon charcoal and exposed to the flame of the gas blowpipe... after suffering it to become cold... the two rubies were melted into one bead.[1]

Across the 19th century attempts had also been made to create man made rubies. A few less fruitful attempts made in the 1830's inspired the head of the chemistry laboratory of the Natural History Museum in Paris, Edmond Fremy, to take up the cause. He managed to produce small rubies by heating the raw materials for ruby in a flux which causes them to dissolve at much lower temperatures. Cooling of the flux, containing the dissolved ingredients, caused crystallisation of rubies. One of Fremy's assistants, Auguste Verneuil finally managed to create large enough crystals of synthetic ruby with a revolutionary method that still bares his name.

Verneuil Ruby showing typical curved striae under magnification


But, not all was artificial. The 19th century brought European miners to the Mogok Valley in Myanmar and large amounts of ruby were mined and introduced to the Western markets.

Contemporary History

The 20th century that has seen a score of inventions that allowed advanced heat treatment techniques, new methods of synthesis and filling techniques to emerge.

Ruby Localities

Major localities for Ruby
Time [2] Locality Comments
Before 543 BC Sri Lanka With hominid habitation going back as far as half a million years ago and proof of stone cultures emerging some 12,000 years ago, it is likely that Sri Lankan's ruby mining history goes back quite a long way. The first Sri Lankan sapphires and rubies to appear in Western jewelry are those set in Etruscan jewelry. Sri Lanka has seen a continuous mining of it's corundum deposits since. Thousands of localities lie scattered over the island and numerous historical references leave no doubt that this island has been the source of rubies for over 2000 years.
Before 600 AD Myanmar When discussing ruby one has to state Mogok as being the ultimate locality for this mineral. Possibly a source for ruby since paleolithic and neolithic times the locality is mentioned in ancient legends. The first Europeans to visit the area and report on the stunning gems lived in the 15th century. The Mogok mines have been subject to short lived European exploitation in the 20th century but are now closed for foreigners. The quality of fine Mogok ruby is equalled by none.

A second deposit was found in 1991 at Möng Hsu although these rubies are often riddled with fractures and are commonly filled.

Before 951 AD Afghanistan Two main localities of which one has been known since at least since the 10th century. Written accounts that discuss ruby mines in Badakshan (on the border with Tajikistan) teach us that these mines were known and being worked since at least that time. The second deposit is situated close to the present capital Kabul at Jagdalek, a locality that seems to have been discovered much later. The earliest mention of them that was found by RWH is from 1881.
Before 1408 AD Thailand/Cambodia Rubies high in iron content have been found in large numbers near Chantaburi, in the south east of the country on the border between Thailand and Cambodia. Their color is often described as dark, or brownish, but the vast quantities of facet grade material caused the mines to be worked heavily during the second half of the 20th century.
After 1891 Madagascar Various localities have produced ruby along with sapphires of all colors. The gems of this geological paradise were first described in 1547 but it has taken the world another 400 years to see the significance of these deposits.
1950 Tanzania From the 1950s on, Tanzania's gem mining has gradually taken on serious proportions. With ruby deposits from the north to the south and all along a 200-300 km wide belt in the east of the country, Tanzania is a very important ruby locality and new deposits are still being discovered to this day. The Gemresearch video presentation below provides an insight into the mining activities of the Winza ruby deposit:

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1973 Kenya Various deposits are scattered over the country but the most important deposit lies at Mangari in the south east of Kenya. Ruby was first discovered at this locality by John Saul and Elliot Miller, two American geologists who claimed a mining lease over the deposit in 1973. They never got to mine it though as the two were quickly chased out of the country when it became clear how significant their find was.
1970's Vietnam The first major discovery of ruby in Vietnam was made in the north of the country in the province called Luc Yen. The potential of the ruby deposits weren't recognized until the end of the 1980's when commercial mining began and the world learned of Vietnam's beautiful rubies.
2008 Mozambique A new ruby deposit has been found at the border to Zambia in Mozambique.


Gemological information

Gemological information for ruby
Color Red
Crystal Structure Trigonal
Family Corundum
Refractive Index 1.762-1.770
Durability Very durable
Hardness 9
Similar stones Confusion is possible with garnet, spinel, red tourmaline and red beryl
Treatments Sometimes heat treated and/or fracture filled, bulk diffusion
Country of origin Myanmar, Madagascar, Australia and many other sources
Ruby care
Ultrasonic cleaning Usually safe
Steam cleaning Usually safe
Warm soapy water Safe
Chemical attack Avoid
Light sensitivity Stable
Heat sensitivity May fracture


Sources Consulted

  • Ruby & Sapphire, Hughes, Richard W. RWH pub, 1997. ISBN 0964509768
  • Gems, Webster, R, edited by Read, Peter. Butterworth-Heinemann; 4th edition (January 1983). ISBN 0408011483

Online G&G articles on ruby

Online G&G articles on synthetic ruby

Notes

  1. E.D. Clarke. 1819 (as quoted by Hughes, 1996)
  2. these dates are to be taken as rough guides only, in most cases it is impossible to put a date on the first discovery of a deposit. The dates signify the European knowledge of a deposit more then it's first discovery
Lang Antiques
Lang Antiques