Topaz

Topaz comes in many colors such as blue, yellow, pink, brown, green and
clear. Orange-red "Imperial" topaz is rare. Blue Topaz is much less
expensive than aquamarine and as such very popular. It looks beautiful in
rings, bracelets, necklaces, and pendants. Topaz looks magnificent with
almost any outfit.

Topaz is a common gemstone that has been used for centuries in jewelry. Its
golden brown to yellow color is classic but is confused with the less
valuable citrine, which is sold under the name topaz. The blue topaz that is
often confused with aquamarine is rarely natural and is produced by
irradiating and then heating clear crystals. Topaz is the November
Birthstone. Topaz crystals can reach incredible size of several houndred
pounds. Topaz can make very attractive mineral specimens due to their high
luster, nice colors and well formed and multifaceted crystals.

Topaz is a fluosilicate of aluminum, occurring in transparent yellow,
yellow-brown, orange-brown, light to almost medium red, very light to light
blue, very light green and violet colours.

Varieties - Coloured varieties, Imperial (reddish-orange), chatoyant
material (very rare).

Sources - Prime source is Brazil. Sri Lanka (blue), Mexico (mostly poor
quality, brownish-yellow), Russia, South Africa (blue), Utah, Afghanistan.

Treatments - Heat and chemical treatments.

History - The stone began to be used in Marco Polo's time (13th century).
Topaz mounted in gold and hung around the neck was believed to dispel
enchantment. When the powdered stone was put in wine, it was considered a
cure for asthma, insomnia, burns and haemorrhages. Topaz was supposed to
become obscure in contact with poison and to quench the heat of boiling
water. All these powers were believed to be increased or decreased with the
changes of the moon.

It has an easy and perfect basal cleavage and so gemstones or other fine
specimens should be handled with care to avoid developing cleavage flaws.
The fracture is conchoidal to uneven. Topaz has a hardness of 8, a specific
gravity of 3.4-3.6, and a vitreous luster. Pure topaz is transparent but is
usually tinted by impurities; typical topaz is wine or straw-yellow. They
may also be white, gray, green, blue, pink or reddish-yellow and transparent
or translucent. When heated, yellow topaz often becomes reddish-pink. It can
also be irradiated, turning the stone a light and distinctive shade of blue.
A recent trend in jewelry is the manufacture of topaz specimens that display
iridescent colors, by applying a thin layer of titanium oxide via physical
vapor deposition.
The Egyptians said that topaz was colored with the golden glow of the mighty
sun god Ra. This made topaz a very powerful amulet that protected the
faithful against harm. The Romans associated topaz with Jupiter, who also is
the god of the sun. Topaz sometimes has the amber gold of fine cognac or the
blush of a peach and all the beautiful warm browns and oranges inbetween.
Some rare and exceptional topaz are pale pink to a sherry red.

Wear topaz only if you wish to be clear-sighted: legend has it that it
dispels all enchantment and helps to improve eyesight as well! The ancient
Greeks believed that it had the power to increase strength and make its
wearer invisible in times of emergency. Topaz was also said to change color
in the presence of poisoned food or drink. Its mystical curative powers
waxed and waned with the phases of the moon: it was said to cure insomnia,
asthma, and hemorrhages.

Perhaps the most famous topaz is a giant specimen set in the Portuguese
Crown, the Braganza, which was first thought to be a diamond. There is also
a beautiful topaz set in the Green Vault in Dresden, one of the world's
important gem collections.

Brown, yellow, orange, sherry, red, blue and pink topaz is found in Brazil
and Sri Lanka. Pink topaz is found in Pakistan and Russia.

Today we also have blue topaz, which has a pale to medium blue color created
by irradiation. Pale topaz which is enhanced to become blue is found in
Brazil, Sri Lanka, Nigeria, and China. In early 1998, a new type of enhanced
topaz made its appearance, the surface-enhanced topaz, with colours
described as blue to greenish-blue or emerald green.

Topaz is the birthstone for those born in the month of November.

Cat's Eye Gemstones

A cat's eye like effect, known as 'chatoyancy', appears to move on this
stone's surface. Cat's eye is a gem variety of chrysoberyl.

There are generally two varieties of cat's eye - the alexandrite cat's-eye
and the chrysoberyl cat's-eye, which is very popular in the Far East,
particularly in Japan. The ideal colors of the chrysoberyl cat's-eye are
yellowish-brown, which is called the honey colour, and the yellow-green,
which is called the apple green colour. A very good cat's eye, apart from
being of ideal color, should have a high degree of transparency and a
well-defined unbroken ray. It should be free from any distracting inclusions
visible to the unaided eye. The chrysoberyl cat's-eye is one of the most
beautiful gemstones because of the "chatoyancy" or the eye effect.

Varieties - Chrysoberyl and Alexandrite, Color change green to red,
Chatoyant, Various shades of green, yellow, brownish, and reddish.

History - Cat's eye has been regarded as a preserver of good fortune. The
natives of Sri Lanka still consider it a charm against evil spirits. British
royalty often use it as an engagement stone.

A translucent variety of chrysoberyl (beryllium aluminum oxide) which
exhibits a silvery white line across the stone. This moves as the stone, the
light source or the observer moves and may appear to open and close like an
eye. The finest quality has a sharp eye that appears to open and close as
the stone is rotated, and exhibits a strong "milk and honey" effect (stone
on one side of the eye appears lighter than the other). These colours switch
as the stone or light source is moved. The most highly prized body colours
are greenish-yellow and brownish-yellow (honey color).
When a gem specimen exhibits both chatoyancy and change of colour, one or
both phenomena will suffer. It is more common to find a good eye with poor
change of color. The conditions necessary for one phenomenon conflict with
those needed for the other. The term cat's eye when used alone refers to
chrysoberyl. Other minerals exhibiting chatoyancy must be qualified, e.g.
tourmaline cat's eye.

Often, the name chrysoberyl is spoken in the same breath as that of the
beryl group, the most well known representatives of which include the
emerald and the aquamarine. The name 'chrysoberyl' comes from the Greek and
means 'gold-colored beryl'. In spite of its name however, it is not actually
a beryl at all. Together with alexandrite, chrysoberyl forms an independent
gemstone, in which the former, which appears to change its colour, is
regarded as the most attractive representative, though in fact it is quite
definitely the chrysoberyl cat's eye which is entitled to stake that claim.

From a mineralogical point of view, chrysoberyls are aluminium oxide
containing beryllium, and thus actually have little in common with the
beryls, which belong to the silicate family. Indeed, with their excellent
hardness of 8_ on the Mohs Scale, they are clearly superior to the beryls.
The popular chrysoberyls come in many nuances between lemon and greenish
yellow, and in honey colors and shades from mint green to brownish green,
and are mostly found in the gemstone deposits of Brazil, Sri Lanka or East
Africa.

Since ancient times, chrysoberyl has been regarded as a gemstone which
protects its wearer and keeps disaster at bay. The cat's eye most of all is
seen as a particularly effective protective stone and talisman. On account
of its golden tones, chrysoberyl is often also associated with wealth - and
this idea is certainly not without foundation, since in its most beautiful
form as a high-quality cat's eye it is up among the gemstones of the luxury
class.

Discipline and self-control are the qualities mainly associated with
chrysoberyl in modern gemstone therapy. Chrysoberyls are said to promote
concentration and the ability to learn, and to enable the wearer to think
clearly and far-sightedly. Thanks to the secret power of the chrysoberyl,
negative thoughts are said to be transformed into positive energy. And these
positive qualities are said to be even more marked with a chrysoberyl cat's
eye. However, chrysoberyl is also regarded as a gemstone which promotes
tolerance and harmony, and it is one of the lucky stones for those born
under the sign of Leo.

Chrysoberyl cat's eyes are genuine rarities which are found only in a few
deposits in the world, together with other varieties of chrysoberyl. One can
hardly imagine that a gemstone could wink like the eye of a cat in such a
remarkably genuine way. Is it magic, or Nature? And apart from that, what is
it that causes this irresistibly beautiful show of light?

Scientists have discovered that very fine inclusions, deposited in the
stone, are responsible for this fascinating phenomenon. The incident light
is reflected off them, so that a bright strip of light appears, running
perpendicular to the inclusions, similar to the eye of a feline predator.
When the stone is turned, this strip seems to glide away across the surface
of the stone. In technical terminology this phenomenon is known as
'chatoyancy', which comes from the French chat (for cat) and oeil (for eye).
Whilst chrysoberyls lacking the cat's eye effect are mostly faceted, cat's
eyes are always cut into cabochons, since only tall, rounded shapes render
the line of the eye properly visible.

The chrysoberyl, with its hues ranging from honey-coloured to mint green, is
a popular gemstone, and one which is esteemed by connoisseurs and gemstone
lovers the world over. In its most attractive variety, the cat's-eye, it is
an extremely valuable stone for those in the know. In general, the value of
a chrysoberyl - as with other gemstones - depends on its quality, that is to
say its beauty, color and attractiveness, the depth of the color and its
transparency. Anyone who wants to acquire a cat's-eye of good colour and
with a finely marked eye-line will be obliged to dig fairly deep into his
pocket, for these gems fetch much higher prices on account of their beauty
and rarity. When buying a cat's-eye, you should be aware of this: it is
important that the 'eye' has a fine line running right through it, and that
it can be recognised clearly. In particularly good specimens, it seems to
open and close when the stone is turned. Fine cat's eyes should be of a
distinctive color and be as transparent as possible. The most popular ones
are those of a beautiful honey yellow and those with fine green tones.

Chrysoberyl cat's eyes are among the most beautiful things that Nature has
created. Again and again, they fire the enthusiasm of those who are looking
for something individual and unique. Cat's eyes are also well suited to
being worn as jewellery by men. And without doubt, there is many a man who
has allowed himself to be seduced by a beautiful cat's eye too

Until recently the main producers of fine quality chrysoberyl were Brazil
and Sri Lanka, but now much more productive mines are in Madagascar and
Tanzania. Because Sri Lanka Chrysoberyl has the finest quality and high
value most of the Madagascar rough is sold as genuine Sri Lanka stones.

When choosing a Chrysoberyl gemstone, due to the pastel color of
chrysoberyl, special attention should be given to the cut and overall
proportions of the stone. When choosing a cat's eye gemstone priority should
be given to the ray or eye of the stone.

Star Gem Stones of Sri Lanka

Star stones of the corundum family are either star sapphires or rubies. When
light falls on these stones, a star effect is visible (known as asterism).

Sri Lanka is the best known source for star sapphires and star rubies. Star
sapphires range in colour from grey to bluish-grey and from medium blue to
medium dark blue. The very slightly purplish medium dark blue is the best
colour grade for star sapphires. Star rubies range from light pink-red to
purple-red through deep purple-red. The intense red star rubies are
extremely rare. A good quality star stone should have a high degree of
transparency and a well defined star with no weak or missing rays. It should
be reasonably clean and in the face-up position, no distracting inclusions
or cracks should be seen. There should be no excess weight at the bottom of
the stone.

Star sapphires and rubies are hard stones (9 on the Moh's scale), which can
take a high degree of polish and retain the shinefor a long time. The
special optical phenomenon of a well-defined six-ray star is a fascinating
sight. The wearable qualities of the star stones make them suitable for
men's rings.

Varieties - Star sapphire, Star Ruby

Treatments - Heat treatments. Treatment of Ruby and Sapphire stones are
permanent.

History - One of the world's finest large example, the Rosser Reeves Star
Ruby, was mined in Sri Lanka. The Star of Sri Lanka (wrong uses as India),
at 563 carats, is the largest and most famous star sapphire in the world.
Formed some 2 billion years ago, it was discovered, allegedly more than 300
years ago, in Sri Lanka. Industrialist and financier J. P. Morgan presented
the sapphire to the American Museum of Natural History in 1900. Today, the
Star of Sri Lanka (India) and the Rosser Reeves Star Ruby resides in the
Morgan-Tiffany Collection in the American Museum of Natural History in New
York City.

The presence of the mineral rutile in the Star of India gives the stone its
milky quality. This also yields the star effect, as tiny fibers of the
mineral, aligned in a three-fold pattern within the gem, reflect incoming
light in the star pattern. This effect is known as asterism, and, along with
color, is one of the characteristics that makes star sapphires so highly
prized. Such stones are polished in the domed shape you can see here, called
a cabochon, to best reveal the star, which moves with changing angles of
illumination and observation.

Star sapphires and rubies are hard stones (9 on the Moh's scale), which can
take a high degree of polish and retain the shinefor a long time. The
special optical phenomenon of a well-defined six-ray star is a fascinating
sight. The wearable qualities of the star stones make them suitable for
men's rings.
Star sapphire is the result of reflection of light from fine, oriented,
rutile needles. Like star ruby, star sapphires may be heat treated to high
temperatures to dissolve the rutile and produce blue sapphires of good
clarity. Such has been the recent fate of much of the Sri Lankan Geuda
material that might have otherwise been uncutable (too dark and/or cloudy).
Unfortunately, some reports state that much of the good star material is now
suffering the same fate. The same characteristics apply to good star
sapphire as to star ruby (see above). The best body color is an intense pure
blue, but such natural stones are rare and one more frequently encounters
blues that are more gray. Fine blues are more translucent than even good
gray-blues and are cabbed thicker as a result. Such stones may appear to be
"overweight" with bulky bases, an important consideration when paying by
weight but a necessity to maintain a deep blue color. This is not the case
for average blue stones, however, and you should not pay for excess weight
unnecessarily.

Choosing a Star Stone

Star Gemstones have long been coveted for their beautiful and mysterious
optical effects. Glance at a star gemstone and you will see four, six or
even twelve rayed stars silently gliding across the gemstone's surface.

This intriguing optical phenomenon is unique to the world of gemstones.
Technically known as the "Asteric Effect", it is caused by sets of parallel
needle-like inclusions of foreign minerals. Sometimes known as "silk", the
needles are oriented in all or some of the directions of the crystal
structure. These needles are responsible for reflecting intersecting bands
of light back to the eye.

Sri Lanka and Burma are the world's top producing Star Ruby and Sapphire
locations. Generally, Sri Lanka for Blue and Fancy Colors, Burma for Red,
Blue and Fancy Colors. However, Star Rubies and Sapphires are found in
virtually all Ruby and Sapphire producing locations. Ranging in quality from
grayed-out colors with indistinct stars, to beautiful color hues with bright
and distinct stars, prices can range from just a few dollars to many
thousands.

The value of star rubies and sapphires are influenced by two factors: the
intensity and attractiveness of the body colour and the strength and
sharpness of the star. All six legs should be straight and equally
prominent. Star rubies rarely have the combination of a fine translucent or
transparent colour and a sharp prominent star. These gems are valuable and
expensive.

Judging the quality and value of star gemstones is best done underneath
singular light sources. Singular light sources such light bulbs, candles,
direct sunlight, spotlights and penlights are ideal to judge star gemstones.
Diffused illumination, such as fluorescent strip lamps, greatly blurs the
effects leading you to make an erroneous conclusion. Avoid making any
judgments underneath diffused lighting. At Thaigem.com all our Star Gems are
selected, described and photographed under single light sources.

The Distinctiveness Of The Star: The star of a gemstone should ideally be
well contrasted against the body color of the gem. The more distinct the
star, the better the quality. The Length & Straightness Of Each Ray:
Straight rays that reach almost girdle-to-girdle are the most desirable and
valuable. In reality, perfectly straight girdle-to-girdle rays are rare.
Color: As always, color is a deciding factor with gemstones. A gem should
have bright vivid coloration that is free from dull overtones and is evenly
distributed across the surface of the Gem. The Cut & Star Position: The
outline of the gem should ideally be regular and well cut around the girdle.

When you look at the star, it should appear to sit in the middle of the gem,
not to one side. Stars that sit on top of the gem are most desirable. Carat
Weight: As always, carat weight affects the per carat price. Higher weights
are more rare than smaller weights and thus command a higher premium per
carat.

Ceylon Ruby

Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide)
in which the color is caused mainly by chromium. Its name originates from
ruber or rubrum, Latin for red. Natural rubies are exceptionally rare,
though artificial ones (sometimes called created ruby) can be manufactured
by the Verneuil process relatively inexpensively. Other varieties of
gem-quality corundum are called sapphires.

Rubies are mined in Africa, Asia, Australia, and Greenland. They are most
often found in Myanmar, Sri Lanka, Kenya, Madagascar and Thailand, though
they have also been found in the U.S. states of Montana, North Carolina and
South Carolina. The Mogok Valley in Myanmar has produced some of the finest
rubies. However in recent years very few good rubies have been found there.
In central Myanmar the area of Mong Hsu also produces rubies. In 2002 rubies
were found in the Waseges River area of Kenya. Rubies are being mined at
Audilamena in northeastern Madagascar. Sometimes spinels are found along
with rubies in the same geological formations and are mistaken for the more
valuable gem. However, fine red spinels may approach the average ruby in
value.

Rubies are generously represented in crowns and scepters in the royal jewels
of many nations. Ruby has acquired special attributes from its admirers over
the centuries. It has been regarded as a symbol of freedom, charity, dignity
and divine power. The Burmese believed that gemstones ripened like fruit.
The redder the color, the riper the ruby. A flawed ruby was considered over
mature. Large, gem quality rubies have always been very rare. The huge gems
described in medieval romances and oriental literature were most likely
exaggerated by the imaginations of ruby admirers and creative authors or
were actually garnets or spinels.

Ruby is the birthstone of July

Treatments - Heat and chemical treatments. Treatment of Ruby stones are
permanent.

History - The Burmese believed that "blazing red" stones could be found in a
"bottomless" valley. Natives threw pieces of meat into the valley, hoping
that some stones could then be recovered by killing the vultures. In the
Royal Collection of England, you can view a gold ring set with a pale but
nearly flawless ruby into which a portrait of Louis XII of France is carved.
According to Rebbenu Bachya, the word odem in the verse Exodus 28:17 means
"ruby"; it was the stone on the Ephod representing the tribe of Reuben.
Modern Hebrew has taken this meaning. [citation needed] Ruby is also the
most commonly named precious stone in the Bible; an example being Proverbs
31: "A virtuous wife is worth more than rubies.

Ruby gemstones are valued according to several characteristics including
size, color, clarity and cut. All natural rubies have imperfections in them,
including color impurities and inclusions of rutile needles known as silk.
If the silk inside of the stone is not there, then one could assume the
stone was heated at a temperature of 3000 degrees. This was done to give the
ruby a better color of red. Usually the rough stone is heated before
cutting. On the other hand, artificial rubies may have no imperfections. The
fewer the number and the less obvious the imperfections, the more valuable
the ruby is; unless there are no imperfections (i.e., a "perfect" ruby), in
which case it is suspected of being artificially made and its status as a
priceless gem is therefore not completely assured. Some manufactured rubies
have dopants added to them so that they can be identified as artificial, but
most require gemological testing to determine their origin.

Rubies come in various shades of red, red purple and red orange. A medium
toned red or red with slight blue is most desired. Clarity of the stone and
inclusions are also taken into account to determined the stones value. Once
the stones looks more toward the color purple or orange then it is called a
fancy sapphire.

Choosing a Ruby - The most important factor in the value of a ruby is color.
The top qualities are as red as you can imagine: a saturated pure spectral
hue without any overtones of brown or blue. The word red is derived from the
Latin word for ruby, ruber, which is derived from similar words in Persian,
Hebrew, and Sanskrit. The intensity of colour of a fine ruby is like a
glowing coal, probably the most intensely coloured substance our ancestors
ever saw. It is no wonder they ascribed magical powers to these fires that
burned perpetually and never extinguished themselves.

Besides color, other factors that influence the value of a ruby are clarity,
cut, and size. Rubies that are perfectly transparent, with no tiny flaws,
are more valuable than those with inclusions, which are visible to the eye.
Cut can make a big difference in how attractive and lively a ruby appears to
the eye. A well-cut stone should reflect backlight evenly across the surface
without a dark or washed-out area in the centre that can result from a stone
that is too deep or shallow. The shape should also be symmetrical and there
should not be any nicks or scratches in the polish. Rubies and other
gemstones are sold per carat, a unit of weight equal to one-fifth of a gram.
Larger rubies, because they are more rare, will cost more per carat than
smaller stones of the same quality.

The Ruby sometimes displays a three-ray, six-point star. These star rubies
are cut in a smooth domed cabochon cut to display the effect. The star is
most visible when illuminated with a single light source: it moves across
the stone as the light moves. This effect, called asterism, is caused by
light reflecting off tiny rutile needles, called "silk," which are oriented
along the crystal faces.

The value of star rubies and sapphires are influenced by two factors: the
intensity and attractiveness of the body colour and the strength and
sharpness of the star. All six legs should be straight and equally
prominent. Star rubies rarely have the combination of a fine translucent or
transparent color and a sharp prominent star. These gems are valuable and
expensive.

The most famous source of fine rubies is Burma, which is now called Myanmar.
The ruby mines of Myanmar date back to centuries ago: stone age and bronze
age mining tools have been found in the mining area of Mogok. Rubies from
the legendary mines in Mogok often have a pure red color, sometimes
described as "pigeon's-blood", although that term is more fanciful than an
actual practical standard in the trade today. Myanmar also produces intense
pinkish red rubies, which are vivid and extremely beautiful. Many of the
rubies from Burma have a strong fluorescence when exposed to ultraviolet
rays like those in sunlight, which layers on extra colour. Burma rubies have
a reputation of holding their vivid colour under all lighting conditions.

Sri Lankan stones are often pinkish in hue and many are pastel in tone.
Some, however, resemble the vivid pinkish red hues from Burma. Rubies from
Kenya and Tanzania surprised the world when they were discovered in the
sixties because their color rivals the world's best. Unfortunately, most of
the ruby production from these countries has many inclusions, tiny flaws
that diminish transparency. Rubies from the African mines are rarely
transparent enough to facet. However, their fantastic color is displayed to
full advantage when cut in the cabochon style. A few rare clean stones of
top quality have been seen.

Occasionally a few fine, top-quality rubies appear on the market from
Afghanistan, Pakistan or the Pamir Mountains of the Commonwealth of
Independent States. The terrain in these areas has made exploration for
gemstones very difficult but someday they may produce significant quantities
for the world market.

Ceylon Sapphires

Sapphire is an aluminum oxide. Its colour varies from very light to dark blue to violetish-blue, bluish-green, yellow, slightly reddish-orange, brown, nearly opaque black, colorless, pink, violet and the pinkish-orange padparadscha (lotus flower).

Ceylon sapphires are part of the Corundum gem family and are second only to diamonds in hardness. This strength makes them an excellent choice of jewelry because of their durability. The sapphires mined in Sri Lanka are known for the unique color they produce. Because Ceylon sapphires occur naturally, the color of the stone varies.

Often, sapphires used in jewelry are heat-treated or given chemical diffusion to enhance their color, these enhancements are permanent.

Sapphire is the birthstone of September

Treatments - Sapphires can be x-rayed to intensify their colour. Natural sapphires undergo heat and diffusion treatments in Thailand. With the first method, sapphires with latent chemical components for good color are "ripened" to a desirable color through heating. In diffusion treatment, sapphires that lack the components for good color are placed in a bath of colouring oxides that penetrate the outer layers of the stone. Treatment of blue stones is permanent.

History - According to an ancient Persian legend, the earth rested on a great sapphire whose reflection was seen in the sky. The stone also appears in the Promethean legend. Prometheus was chained to a rock by Zeus for having stolen fire from the gods. After being rescued by Hercules, a link of the chain remained on his finger, and attached to it was a piece of rock. Zeus agreed to grant Prometheus his freedom if he wore the link as a reminder of his sin. Later a ring set with a sapphire replaced the link and stone. Sapphire symbolizes truth, sincerity and constancy. It was believed to protect the wearer against capture by an enemy, and to win the favor of princesses. It also protected against poison. It was said that if a poisonous snake were put in a vessel with a sapphire, the rays from the gem would kill it. The name sapphire originally comes from Sanskrit. It became sappheiros in Greek, meaning blue. Before the value of sapphire was known to them, villages in the Zanzkar mountains of Kashmir (India) used the gem as a flint to start fires.

The Ceylon Blue Sapphire is known for its beauty – possessing the glorious cornflower blue shade – as well as for being one of the few sapphires in the world that can be sold as a completely natural stone without heat treatment. The blues aside, Ceylon sapphires also come in beautiful hues including pink, yellow, orange, green, purple, lavender and of course, the inimitable padparadscha sapphire – named after the lotus flower. All these highly marketable qualities of Ceylon sapphire has created brand recognition world wide - a brand not created by the producers of the stone, but by the sellers and consumers.

Sapphires that show a star-like light effect are called star sapphires; the most famous star sapphire from Sri Lanka is displayed in the Museum of Natural History in New York. Star sapphires or star rubies display a star-like marking and this effect, commonly known as asterism, occurs when light falls on the cut stone, cut in the cabochon form, and three rays appear giving a six-point star. However, stones with six rays have also been known to occur.

Lastly, there is milky corundum, a white opaque form of corundum also called geuda, which for many years was regarded as useless and discarded, often ending up lining fish tanks in some gemstone merchant's house. This happened until dealers in Thailand learned to heat-treat geudas to change the colour of the stone from an unattractive cloudy grey-white to a bright, sparkling blue. They completed the work nature began and ended up with a blue sapphire - of much greater value than a useless pebble. The color of heat-treated blue sapphires are stable and the chemical composition of the stone is that of a sapphire, although prices are lower than for a similar quality stone with natural color.

Choosing a Sapphire

The most famous sources for sapphire are Kashmir and Burma, (now known as Myanmar). Kashmir sapphire, which was discovered in 1881 when a landslide in the Himalayas uncovered beautiful blue pebbles, has a rich velvety colour prized by connoisseurs. Burma sapphires, from the same region that produces fabulous rubies, are also very fine. However, today, these two sources account for a very small quantity of the sapphire on the market.

Most fine sapphire on the market today comes from Sri Lanka, which produces a wide range of beautiful blues from delicate sky blue colors to rich saturated hues. Kanchanaburi in Thailand and Pailin in Cambodia are renowned for deep blue, even colors. Two relatively new mining localities are showing promise: Madagascar, which has produced some exceptionally fine stones in small sizes but has no organized mining yet, and Tanzania, which has long produced sapphire in other colours but is starting to produce blue colors as well from a new deposit in the south.

The most valuable sapphires have a medium intense, vivid blue colour. The best sapphires hold the brightness of their colour under all different types of lighting. Any black, grey, or green overtones mixed in with the blue will reduce a stone's value. In general, a more pastel blue would be less preferred than a vivid blue but would be priced higher than an overly dark blackish-blue color. As with all gemstones, sapphires, which are "clean" and have few visible inclusions or tiny flaws are the most valuable.

Sapphires are most often cut in a cushion shape - a rounded rectangle - or an oval shape. You can also find smaller sapphires in round brilliant cuts or a wide variety of fancy shapes, including triangles, squares, emerald cuts, marquises, pear shapes, baguette shapes, cabochon cuts and smooth domes.

HK fair feels impact of Indian diamond market's liberalisation

Diamond suppliers from all over the world are starting to reap the benefits of a liberalised Indian diamond market. According to exhibitors at the September Hong Kong Jewellery and Watch fair, which concluded on Saturday, the waiving of the import duty on diamonds entering India in May has brought in a big number of diamond buyers from India.