Some
gem types, particularly Sapphire, ruby, emerald and red tourmaline, are practically non-existent without some form of inclusion.
Some are even valued for their inclusions, so don’t worry, the
gem industry and it’s price structuring takes this factor into
account.
Clarity is a subjective term, however the
following is how we describe clarity:
Opaque: the gemstone will
not transmit light through it.
Translucent, or cloudy:
the gemstone transmits light, but you cannot see clearly through
it.
Heavily Included: the gemstone is transparent, but the gemstone is littered with inclusions,
which are very visible without magnification.
Moderately Included: the
gemstone is transparent, but there are several inclusions, which
are visible without magnification.
Slightly Included: the gemstone has some very minor inclusions, which may be visible without
magnification.
Very Slightly Included (Eye-Clean):
the gemstone has some very minor inclusions that are not readily
visible without magnification. Some Inclusions may be visible
without magnification once you see them under magnification
and know exactly where to look.
Very Very Slightly Included:
the gemstone has some very very minor inclusions which are difficult
to see under magnification.
Loupe Clean (Clean): no
inclusions were seen using 10x magnification. However the gemstone was not examined microscopically. The gemstone may be internally
flawless or flawless.
Internally Flawless: the
gemstone was examined under a microscope of at least 40x magnification,
and no inclusions were seen. The gemstone has some external
blemishes.
Flawless: the gemstone was examined under a microscope of at least 40x magnification
and no inclusions were seen and the gemstone has no external
blemishes.
The measure of visibility through
a Sapphire is known as its transparency. It is an often-overlooked
characteristic when discussing Sapphire. Sapphires are often
lightly included and commercial quality can be translucent to
opaque.
Transparency is designated
as follows:
• Transparent - objects look clear through the gemstone. These Sapphires boast superb brilliancy in spite of
any inclusions they may contain.
• Semitransparent - objects appear somewhat hazy or
unclear through the gemstone.
• Translucent - objects are hard to see through the
gemstone. Light can pass all the way through, but it
is fairly diffused.
• Semi-translucent or semi-opaque - a small fraction
of light passes through the gemstone.
• Opaque - almost no light passes through the gemstone.
|
|
What if the clarity and the development of phenomena
of a Sapphire are enhanced by heat- treatment?
Heat treatments, wrongly construed as being artificial,
mirror the exact same processes that occur in nature.
In today’s gem and jewelry industry heat treatments
that have proven to be stable are widely practiced and
accepted.
Ever since demand grew Sapphire’s have been artificially
treated to improve their color and clarity. In fact
it is safe to say that 99% of all Sapphire gems, which
are processed and cut today have been subjected to some
form of heat treatment.
Corundum, whether Sapphire or Ruby, is routinely heated
at temperatures that range from anywhere between 700
to 2000 degrees Celsius. Modern heating units reach temperatures
close to the melting point of corundum: 2050 degrees Celsius.
Because fine inclusions cause some gemstones to look
cloudy, heat treatment that dissolves the inclusions
may also improve the clarity of the gemstone or intensify
inclusions to enhance phenomena such as asterism
• Unwanted rutile and ‘silk’ can be melted out and
dissolved within the crystal structure by heating the
corundum to about 1,600 degrees Centigrade, followed
by rapid cooling.
• Corundum can also be heated in order to crystallize
rutile within the gemstone. If the gemstone contains
sufficient rutile, some may crystallize to allow asterism
to be developed. Rutile crystallizes when corundum is
heated to about 1300 degrees Centigrade, in an oxidizing
(oxygen) atmosphere followed by leisurely cooling.
|
Previous Page
|
Next Page |
|
View The Ruby Collection |