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Ruby
Al
2O
3 Corundum
Ruby Appearance
Rubies are the red variety of the mineral corundum, or aluminum oxide.
The color will vary from an orange-red to a red with a purple tone. If
the color strays too far into the pink or purple tones, it is considered
a sapphire, and the value diminishes significantly. The stone will range
from transparent to virtually opaque depending on the quality. Top
quality stones will be a pure transparent red whose color is incredibly
vibrant especially in bright sunlight. Assuming the stone is free of
inclusions and is not translucent, the ruby is judged by its color. A
true red with just a hint of blue, sometimes referred to as "pigeon's
blood" will command the highest prices. These stones are almost always
from Myanmar, and tend to display fluorescence in daylight that gives
its color a special vibrancy that rubies from other locations in the
world do not have. Low quality stones are often cut in cab forms and
will display a luminous star form or asterism due to the presence of
other materials such as rutile, within the gem's molecular structure.
Due to the ever increasing demand, these stones will often be heated to
dissolve the rutile, and then faceted.
Ruby Occurrence
Approximately 70% of the worlds ruby production is from Thailand. These
stones tend to be darker, sometimes brownish red when compared to the
top quality stones of Myanmar (Burma). Production of Burmese rubies was
at its zenith from about 1890 to 1930 then slowed until the communist
government banned mining in 1962. Mines were nationalized and re-opened
for limited production in 1963. Rubies from Sri Lanka, the second
largest ruby producer, are often of a medium or light color, just on
the ruby side of the ruby / sapphire color split. Rubies are produced
in smaller quantities in Vietnam, Kenya, Tanzania, Australia, India,
Madagascar, Pakistan, Afghanistan, Nepal and North Carolina.
Physical Properties of Ruby
| Composition
| Al2O3
| Class
| oxide
|
| Specific gravity
| 3.98 to 4.10
| Refractive Index
| 1.76 to 1.78
|
| Birefringence
| weak 0.007 to 0.010
| Pleochroism
| very distinct
|
| Cleavage
| none
| Fracture
| conchoidal, brittle
|
| Luster
| adamantine to vitreous
| Transparency
| transparent to translucent
|
| Streak
| white
| Fluorescence
| Strong
|
| Crystal system
| hexagonal-rhombohedral
| Twinning
| common
|
| Hardness
| 9.0
| Dispersion
| .018
|
| Color
| Red
|
| Crystal habit
| tabular, terminated by basal pinacoids,
pyramidal and rhombohedral faces may be partly or entirely absent.
|
| Other
| Inclusions are common, and are often useful in
determining the authenticity of a stone, if not the locale of its
origin.
|
Formation of a Ruby
Rubies are found in a variety of geological settings, but always in
aluminum-rich and silica-poor rocks. It is found as an accessory
mineral in metamorphic rocks derived from aluminous or carbonate
sediments such as crystalline limestone and marble, mica schists and
gneisses. It is also found in contact zones between igneous rocks and
limestones.
Ruby History
The name Ruby is from the Latin word ruber meaning red. One of the
oldest gems recognized, it was called ratnaraj or ratnanayaka, the
'King' or 'Leader' of precious stones in Sanskrit writings. It has
been mined in the Mogok region of Myanmar, or Burma, since at least
1200 AD, and possibly back into prehistoric times based the stone and
bronze age mining tools that have been found in the area.
Ruby Lore
Ruby is considered the symbol of freedom, charity, dignity and divine
power. Said to inspire love, enhance creativity, wisdom and
spirituality, give confidence, self-esteem and courage, and to
stimulate leadership qualities. Rubies were said to preserve health
and provide the wearer invulnerability from wounds, and guarantee that
one's status and possessions would never be taken. It was said to
signify manliness, nobility and valor in a man, and pride & passion in
a woman. It was also reputed to be helpful in treating heart and
circulatory disease. At one time, it was believed that a ruby ripened
like fruit; the redder the color, the riper the ruby. A flawed ruby was
considered over mature.
Other
A top quality ruby is possibly the rarest of gemstones and will fetch
the highest price per carat of any gemstone sold. In the past decade,
nearly a dozen diamonds weighing over 50 carats each have sold at
Sothby's Auction House - top price paid: $125,000 per carat for a 102
carat pear shaped specimen. In approximately the same time frame, only
a few noteworthy rubies have sold - the first a 16 carat stone for
$227,000 per carat and the second, a 27 carat stone mounted in a ring
sold for $4,000,000, or nearly $148,000 per carat and a third, a 32
carat stone for $145,000. Retailers will often sell top quality one
carat stones for between $1000-$7500 per carat. Two-carat stones range
from $3500 to $15,000. Three carats will set you back between $4500 and
$20,000 per carat. Anything larger that is truly a top quality stone
will start at around $20,000 per carat. Sizes above five carats are
exceedingly rare.
Copyright © 2005 by Gem And Mineral Info.com.
All descriptions and images, except where noted, are the property of
Gem And Mineral Info.com
Where noted images and descriptions are used with permission of copyright
holder as indicated.
