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Star Sapphire @ Jewel Info 4 U
By: Nasrina Parvin Khan
INTRODUCTION OF STAR SAPPHIRE
Sapphire- the heavenly stone of this
Earth is one of the most precious
stone among the gems.
Sapphire is the single crystal form
of Aluminium oxide (Al2O3), a
mineral known as corundum. The heat
and the pressure depths of the
ground help the pure Aluminium oxide
to crystallize into beautiful and
splendid white gemstone since the
age. Small amounts of other elements
such as chrome and iron are the
reason to turned this white crystal
into colorful. Sapphires available
in sky blues or sunset colors. The
color of sapphires may be blue, red,
yellow, pink purple, orange or
greenish color.
Rubies are also part of corundum
group. There was a debate which
stone may be termed as a sapphire
for long years. Finally it was
decided that ruby-red sapphires
would be "Rubies" and all other
colors would be "Sapphires".
Though sapphires are available in
various colors, but the most popular
color of sapphires is blue.
When we talk about sapphires, most
people will think about blue.
Sapphires other than blue are known
as 'fancy'. So fancy sapphires
referred to yellow, pink, purple,
green, black or white sapphires.
The most important characteristic of
sapphires is its excellent hardness.
Moh's scale shows the hardness grade
9. The hardness of sapphire placed
with ruby just after the diamond.
Sapphires are easy to care and
handle because of their great
hardness.
Usually sapphire occurs in
sedimentary limestone, metamorphic
marble, and igneous basalt,
pegmatite or andesine dikes.
Naturally corundum mined from
secondary alluvial deposits and
rarely from primary deposits.
There are various kinds of
sapphires, like- "Blue sapphires",
"Fancy sapphires", "Padparadsha",
(means lotus flower)-an orange color
variety of sapphires with a fine
pinkish undertone and very unique
"Star Sapphire".
BLUE SAPPHIRES
The main color of sapphires is blue.
It is the most popular color of
sapphires also. In the ancient time,
every blue gem material was called
sapphire. As for example we can say
the name of Lapis lazuli. So, the
name "Sapphire" derives from the
Greek word 'Sappheiros', which means
blue.
Blue is the most desired color of
sapphires. This gems available in
all the shades of blue skies, from
the deep blue of evening skies to
the bright and deep blue of a clear
and wonderful summer sky. Blue
fascinates all the people. Actually
blue is the favorite color of about
50 per cent of the population in
this World. This color has a strong
association with emotions such as
sympathy and harmony, friendship and
loyalty. These emotions represent
anything permanent and reliable. So,
the sapphire blue has become the
color of permanent and reliable
things. Thus the women in many
countries decide on sapphire for
their engagement rings.
STAR SAPPHIRE
 Most of the blue sapphires are found
in the form star sapphires. Star
sapphire is a variety of sapphire
that shows a star like special
optical phenomenon named as
"asterism".
It is a rare variety of sapphires.
Nearly 3 stars are discovered in
every 100 faceted corundum mined.
Though Star Sapphires are more
common than the Star Ruby. But finer
colored stone with fine star is very
rare. Except blue, star sapphire is
also available in black.
"Asterism" is a phenomenon by which
a star shaped light effect has been
shown across the surface of the gem
through the reflection or
transmission of light.
Star Sapphire is one of the most
popular star gems, which shows an
illuminated, wavy star bellow the
surface of the crystal.
Usually Star Sapphire shows the six
legged star effect. But it can shows
four to twelve rays depending on the
crystal system of the gems. Twelve
rays star effect in sapphire is very
occasional.
WHAT CAUSES STAR EFFECT
Star effect or "asterism" is caused
by the dense inclusions of tiny
fibers of foreign particles in gems.
Generally, these inclusions are the
reason of the reflection of light
and form a wavy star like formation,
which moves around when the mineral
is rotated. All the inclusions in
the gem are form via exsolution.
Solid crystal inclusions found
within the corundum sapphire. Some
sapphires leave holes or empty areas
in the host, which filled with
liquid, gas or solid. Reflection
creates from fibers or fibrous
cavity in the crystal.
The inclusions must be long, very
thin needle like which called as
'rutile'. "Asterism" is produced
when the light is concentrate into 3
rays that intersects at right angles
to the direction of the needles.
Thus we get a six-rayed star. Small
needles of rutile sometimes called
'silk' are oriented inside the
minerals in the direction of the
crystal growth system. There is
relationship between the gem's
growth and the number of rays
produced by the reflected light.
The arrangements of needles in a
hexagonal pattern produced six-rayed
'asterism'.
Exsolved inclusions form a pattern
in the host mineral to form a star.
This pattern remains same in case of
sapphire. The rays of star should
cross at the top of the sapphire and
must be distinct.
QUALITY OF A STAR
The sharpness and the size of the
star in sapphire depend on the
quality and quantity of rutile
needles. We get a better star in
sapphire when the rutile packed more
densely. Longer needles also produce
a better star than the tiny
particles. When the quantities of
needles are much more, sapphire
turned into a low translucent stone
and lack 'asterism'. It also harms
the color of sapphire.
CUTTING OF A STAR SAPPHIRE
Cutting is very important to exhibit
the star effect in sapphire. Proper
cutting helps to extracts the beauty
of the gem. To display the star
effect in best way, a sapphire must
be cut as cabochon with the girdle,
parallel to the needles. Medium to
high cabochons need to be cut to get
a perfect star in sapphire. The
domed must be round or oval shaped.
COLOR OF STAR SAPPHIRE
Generally Star Sapphires are
available in blue. But other colors
can also be seen. The color of ruby
is red. Star Sapphires are also
available in black, purple, and grey
and so on. Varieties of blue colored
Star Sapphires are found. Star
Sapphires from Sri Lanka are light
blue or grey.
VALUE OF STAR SAPPHIRE
The carat weight is not the only
factor that decides the value of a
star sapphire. It also depends on
the body color, intensity and the
visibility of the star as well as
the strength and sharpness of the
star. All six legs of the star
should be straight and prominent.
Heat treatment is always used to
produce, intensify or lighten color
or improves color uniformity and
appearance of blue sapphire. But
some people preferred untreated,
natural stone.
A good Star Sapphire should be eye
clean and have velvet like softness,
as opposed to diamond like
transparency.
The market value of a sapphire is
also depends on its origin.
Sapphires mined from Sri Lanka are
the most valuable.OCCURRENCE OF STAR SAPPHIRE
Finer qualities Star Sapphires are
found in Myanmar (Burma), Thailand,
India, Sri Lanka, Tanzania,
Afghanistan, Brazil, Cambodia,
Malagasy Republic, Malawi, Pakistan,
Rhodesia of Zimbabwe and Montana and
North Carolina of US. But the best
quality Star Sapphires are available
in Sri Lanka.
FAMOUS STAR SAPPHIRE
The most famous and largest cut star
sapphire is 543-carat "Star of
India". The "Mid night Star"- a
black sapphire is also famous one.
Both of these Star Sapphires are
housed at the American Museum of
Natural History in New York City.
330-carat "Star of Asia" at the
Smithsonian is another famous Star
Sapphire in the world..
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