SOURCES OF STAR
CORUNDUM
The main source of star ruby
and star sapphire is Sri Lanka,
and most material has a light
body color. Small quantities
of high-quality star ruby and
star sapphire with distinct
body colors are mined in the
Mogok region of Myanmar and
polished without treatment.
On the other hand, large quantities
of low-quality Indian star
ruby and black star sapphire
are also available in Bangkok. |
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Weight
: 2.64 ct
Size (mm) : L 7.6 x W 7.2 x
D 4.95
Untreated
US $500 |
Violet Star Sapphire
This material is available
in relatively high levels
of transparency. Comparing
violet star sapphires to
Indian star rubies helps
one understand the considerable
effect that transparency
has on beauty. Because the
cabochon surface of the sapphire
in the photograph is relatively
flat and wide, a star resembling
an open umbrella appears
across the whole surface
of the stone when a strong
light is shined on it. It
can be appreciated as a gemstone
when viewed from above, but
the depth of its base seen
from the side is a cause
of concern.
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Indian Star Ruby
From a mineralogical standpoint,
this is the exact same corundum
as any other star ruby, but it
differs in both its appearance
and beauty. Star ruby is semi-transparent
to translucent, but Indian star
ruby is nearly opaque. This is
the main reason for its low level
of beauty. Because supplies are
so abundant, Indian star ruby is
an inexpensive gem material. Buyers
enticed by the name "ruby" should
realize that Indian star rubies
are useless as jewelry material. |
Weight
: 2.83 ct
Size (mm) : L 7.9 x W 6.1 x D 5.38
US $40 |
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Weight
: 1.09 ct
Size (mm): L 5.9 x W 5.6 x D
2.77
US $8 |
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JUDGING QUALITY
The key to judging quality is simply
to compare a number of star rubies
and determine their level of beauty
and depth of color. Specifically,
there are five factors to consider:
1. Color
2. Quality of Star (Is the star distinct
even under weak lighting?)
3. Transparency
4. Shape
5. Positioning of Star (Is the star
centered on the cabochon?)
It is important that these five factors
are all satisfied in a well-balanced
manner. Even with a distinct star,
material that has a grayish or brownish
body color constitutes low quality.
However, as long as the star is even
barely visible, material with a fine
body color can be used in jewelry. |
Black Star Sapphire
Minute, needle-like inclusions of
minerals such as hematite (a form
of iron) act in a similar fashion
as silk inclusions, causing a star
to appear. In actuality, the sapphire
is yellow, golden, or green, but
its various inclusions cause it
to become a dark brown or black
star sapphire. Diopside, a similar-looking
brownish mineral, may also show
a 4-rayed star. Both of these materials
are extremely inexpensive and sold
as gift items. They may be thought
of as stones that border between
gemstones, which by definition
are 'beautiful and rare,' and common
minerals. |
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