History & Introduction
Moonstone is a popular variety of gemstone of orthoclase feldspar, a potassium aluminum
silicate. This gemstone is from transparent to opaque oligoclase, which is a variety
of plagioclase albite and sheet mica. Moonstone gemstone is famous for the display
of a distinct sheen under certain conditions related to lighting, and it is the
sheen that renders the stone as one of the most remarkable gemstones available at
present. In fact, its name is owed to the almost magical, bluish white shimmer it
shows that closely resembles as of the moon. Gemmologists refer to the shimmering
phenomena as 'adularesence'.
In India it is a sacred stone for the lovers, and is even known to be a "dream stone"
that brings beautiful dreams. Sometimes in Arab countries women do wear moonstone
gem for fertility purposes. It was even believed to be particularly protective to
seafarers, who have used it since ancient times. In the time of full-moon, moonstone
is very powerful for unification of love - and when the moon decreases, is believed
to allow one to predict the future.
The effect related to optical of adularesence is because of unique structural pattern
of moonstone. Albite with tiny inclusions and sodium aluminium silicate are intermixed
with host rock layers of orthoclase, a potassium aluminum silicate. Lamellar (scaly)
structure is formed with the alternating layers of different feldspars, which causes
the interference of light as it enters the stone. Thin layers of alternating silicates
lean to refract more attractive and colourful sheens, while thick layers of silicates
produce less attractive, from white goes with colourless sheens. When light enters
the stone, it gets refracted as well as scattered, which produce a very unique and
attractive play of both light and colour. With moonstone, the aura of light actually
look in to glow from deep within the surface of the stone. Moonstone was very famous
during the time of "Art Nouveau" that took place more than 100 years ago. It was
used in the making of jewellery created by the famous French Master-Goldsmith, René
Lalique, and other contemporaries of his time.
Recognise - Moonstone gems are identified with the presence of
adularesence. Other gems with a look that is alike do not have the phenomenal presence
of adularesence that makes identification of moonstone is very easy. Moonstone gem
consist of a composition of potassium aluminum silicate and is easily identified.
Testing for hardness is frequently taken as the easiest methods for distinguishing
moonstone from other materials. Other similar gems like opal, ammolite or chalcedony
are significantly harder or softer than moonstone. High quality moonstone shows
an incredible "three-dimensional" depth of colour that no other gemstone can imitate,
forming a moonstone almost unmistakable.
Availability - The deposits of moonstone are often found as constituents
in feldspar-rich granitic and syenitic pegmatites across the globe. Still maximum
moonstone deposits are from India and Sri Lanka. Other important sources of deposits
are Germany, Australia, India, Brazil, Myanmar (Burma), Switzerland, Madagascar,
Tanzania, Mexico, Norway, and the United States. Sri Lankan moonstone is most famous
because of the attractive blue colour material, however blue moonstone is becoming
rare with time. India is famous to produce fine 'rainbow moonstone'. Switzerland's
Adula Mountains gives the maximum interesting moonstone mines.
Buying Guide
Color - Naturally, moonstone is colourless, however it is available
in a wide variety of colours that includes yellow, grey, mocha brown, pink, orange,
green, blue and white. Many times it shows a white to bluish-white sheen, however
other sheens can occur such as silvery and blue-orange. The moonstone from Sri Lanka
is in pale blue sheen on a near-transparent body are the most precious one. India's
moonstones exhibit a cloudlike plays of light and colour that are very precious
that includes orange, beige brown, simple brown or green. Colours that are rare
are smoke, blue, champagne, peach, red and black.
Clarity and Lustre - The clarity of moonstone naturally is available
in translucent. Transparent specimens are not available in general, however it is
unheard of. Transparent moonstone is the most precious one. Moonstone possess an
attractive vitreous to pearly lustre once it is cut and polished. Some moonstones
shows chatoyancy. These are known as 'cat's eye moonstone' during trade. With the
asterism effect we get the other rare varieties of moonstone. They are related to
'star moonstone'. Cat's eye and star moonstones are remarkably rare and highly in
demand.
Cut and Shape - Moonstone is always cut into en cabochon to maximize
the required effects of adularesence. The orientation of the cut with moonstone
is very important. It is essential to show the peaked light reflection along with
a genuine height of the stone that is why most moonstone is cut with a high dome.
The crystal axis must locate precisely by the cutters in the zenith of the stone
in order to get the perfect orientation resulting in m the maximized schiller effects.
Very often the moonstone gives the cut in oval shapes since ovals tend to preserve
the maximum weight in carat. There are some faceted stones that are highly transparent,
however faceted moonstone is very rare.
Treatment - Moonstone is not treated or enhanced in any way, still
there are reports of bright blue moonstones that is 'coated' for colour-enhancement.
Gemmological Characteristics: