November Birthstones: Topaz and Citrine

Topaz is the birthstone for the month of November, and those born under the star sign of Sagittarius

There is limited consensus on where the name Topaz originated. The most plausible is that it is named after an island in the Red Sea formerly names Topazos, although today know as Zebirget. The complication arose from a time when all yellow, brown and even green stones were collectively known as “Topaz”.

Topaz comes in many colours naturally, including clear, brown, yellow, orange, red, pink and blue. The most common colour is yellow with a red tint; the most valuable is pink to reddish. The colouring agents are iron and chromium.

The fine golden-yellow variety, known as Imperial Topaz, is relatively scarce. Topaz colours are rarely vivid, and as such the vast majority of today's commercially available cut stones have been enhanced, including those we sell on our website.

Pure Topaz is colourless and transparent; it is only with the inclusion of impurities (trace elements) in the crystal lattice that colour is imparted to the stone. The common colours are brown, yellow, golden, orange, red, pink and blue. The coloring agents are iron and chromium.

Blue topaz

While natural blue topaz is rare, pale blue, pale yellow and white stones are commonly treated to produce the popular blue colours sold as: Sky Blue, Swiss Blue and London Blue.

Blue Topaz 10.00mm Round, 4.97 carats

White Topaz:

This naturally occurring colourless variety of Topaz has enjoyed tremendous interest in the past five years. As a natural, semi precious alternative to Diamond or White Sapphire, this stone is a cost effective alternative in everyday jewellery where a white stone is required.

White Topaz 10x5mm Marquise, 1.15 carats

Mystic  Topaz:
Displaying a kaleidoscope of iridescent colors, Mystic Topaz (also known as Mystic Fire Topaz), was first launched to the public in 1997. The popularity of Mystic Topaz increased dramatically when it was exhibited at the Tucson Gem Show in 2003.

Mystic Topaz is produced using a metallic vapor deposition coating process. This coating is applied to typically only the top (crown) of a facetted white Topaz. The treatment while hard wearing is only 1 micron or so thick, and can become abraded or even removed following polishing of the stone (when jewellery is cleaned), or from everyday wear and tear that will impart micro scratches to the stone surface, effectively cutting through the coating. The stones iridescent appearance changes depending on the light source and the viewing angle, adding to the fire effect of the treatment.

In addition to the iridescent fire colours, brilliant shade or blue, green and orange among others are also currently  being produced and marketed.

Mystic Topaz 12.00mm Round Concave Cut, 6.97 carats

Imperial topaz

This the most sought after of all natural Topaz. Its rich golden color is generally not enhanced by any kind of treatment.

Pink topaz

Natural pink Topaz is very rare and costly. The vast majority of pink topazes are heat-treated yellow stones that turn pink. Pink Topaz is also being produced in large quantities using a similar vapour depositing process as Mystic Topaz, this to satisfy the current worldwide demand for pink coloured stones.

Pink Topaz 12x12 Heart, 7.45 carats

Topaz is a very hard gemstone (8 on the Moh's scale) with a high refractive index thus making it ideal as an everyday gemstone.

Colour
For totally natural stones  the golden-yellow variety, known as Imperial Topaz,  yellow with a red tint or the most valuable pink to reddish stones are popular albeit at a price premium due to their scarcity. Without doubt the most popular colour is Blue topaz, followed by Pink and then the Mystic colours (all being enhanced stones)

Lighting
Topaz is a pleochroic stone, exhibiting different colour when viewed along different axis. No discernable difference is seen between natural and artificial light sources for viewing the stone.

Clarity
Topaz is a Type 1 clarity gemstone and as such only eye clean examples should be considered for purchase.

Cut
Topazes are generally  cut in the simple step cuts, although any cut can be encompassed. The cutting style for weakly colored stones tends to be the round brilliant cut, which imparts more colour to the stone, or any of the cuts where additional facets have been added to enhance the lustre.
Mineable Deposits

While the 18th century deposits of Saxony are today all but depleted, other major deposits had been found to replace the significant consumption of this gemstone. The largest current deposits are in Brazil (Minas Gerais, Esperito Santo)  Other significant deposits are located in Sri Lanka, Myanmar and Russia, with lesser deposits in Afghanistan, Australia, China, Japan, Madagascar, Mexico, Namibia, Nigeria, Pakistan, United States and Zimbabwe. Natural light blue topaz is also found in England (Cornwall), Northern Ireland and Scotland.
Topaz – Common Treatments

The most common treatments for natural rough Topaz  (colorless or very lightly tinted), is either neutron irradiation or  linear acceleration. which are use to create the Blue Topaz commonly available in most jewellers nationwide. Neutron irradiation  followed by stabilisation with heat is use to produce the Swiss Blue Colours (Baby Swiss, Light Swiss, Swiss, Top Swiss) through the strong blue colours (Korean Blue & Maxi Blue) to the dark London Blue Topaz (blue with a green/grey overtone) . The depth of colour in neutron irradiation is a function of  the length of time the rough material is exposed to the isotope Cesium 137. As reactor time is expensive so the darker colours  are sold at a premium over their light  counterparts. The perennially popular Sky Blue Topaz is enhanced using LINAC (linear acceleration) a less expensive enhancement method result in an Aquamarine coloured stone .

In  1997, a new type of enhanced Topaz made its appearance, the surface-enhanced Topaz, with colors described as blue to greenish-blue or emerald green.

The vast majority of pink Topazes are either heat-treated yellow stones that turn pink, or are the result of  a metallic vapor deposition coating process.

Displaying a kaleidoscope of iridescent colors, Mystic Topaz (also known as Mystic Fire Topaz), was first launched to the public in 1997. The popularity of Mystic Topaz increased dramatically when it was exhibited at the Tucson Gem Show in 2003. Mystic Topaz is produced using a metallic vapor deposition coating process. This coating is applied to typically only the top (crown) of a facetted white Topaz. The treatment while hard wearing is only 1 micron or so thick and can become abraded or even removed following polishing of the stone (when jewellery is cleaned), or from everyday wear and tear that will impart micro scratches to the stone surface effectively cutting through the coating. The stones iridescent appearance changes depending on the light source and the viewing angle, adding to the fire effect of the treatment.
Important & Famous Topaz

Topaz is a gemstone who's formation allows for the growth of some very large crystals. In 1967 a Blue Topaz of nearly 100kg (500 000 carats) was discovered in the Ukraine. The Smithsonian Institute in Washington has several large examples on display, including a single facetted stone weighing 22,892.50 carats, making it the largest cut yellow topaz in the world.

Perhaps the most famous Topaz is a giant specimen set in the Portuguese Crown, the "Braganza", which was first thought to be a diamond.
Topaz – The Legend

There are many  ancient stories and beliefs that have created an interesting history for Topaz. The Egyptians called Topaz the “Gem of the Sun,”  and believed it was colored by the golden glow of their sun god Ra and thus a powerful protector from harm.

Greeks and Romans also associated  Golden Topaz with their sun god, Jupiter. They believed the gem increased their strength and could neutralize spells and curses.

Topaz is mentioned in the Bible as being one of the “stones of fire” (Ezekiel 28:13–16) that were given to Moses and set in the breastplate of Aaron (Exodus 28:15–30). Topaz is also one of the twelve gemstones set in the foundations of the city walls of Jerusalem (Revelations 21:19) and associated with the Apostle Matthew.

Bushmen here in Africa used topaz in healing ceremonies and rituals to connect with ancestral spirits.
Topaz is the birthstone for November, and for those born under the star sign of Sagittarius.

Taken from www.touchstonegems.co.za

New Nigerian Red Tourmaline Find

Taken from: Gemstone Forecaster
Author: By Robert Genis

 
The Brazilian red tourmaline, Ouro Fino, was originally found in 1981. It was a killer red colour that looked like a ruby, but the goods were included to a degree similar to Colombian emeralds. Even with the inclusions, collectors coveted the gemstone. The mine was played years ago and the best stones are now sitting in collections. Many new gem dealers have never seen this stone. Red tourmaline was recently discovered in Nigeria in 1998. It came in purple, cranberry, orange/pink and multi colours. This material is long gone and most are sitting in collections or mounted in jewelry. Regretfully, none of this material was ever really red. Since the 1998 find, most of the Nigerian tourmaline material has been very low quality. The yield was low and most of the stones were cabochon quality. Last year, some very large pieces of the new red tourmaline were found in the Oyo Valley of Western Nigeria. Crystals weighing 15 and 48 pounds were found. This is unbelievable! Usually a few pieces are found here and there. The material was so large, the owners needed a tile saw to cut them. The new material is yielding about 15-20% from the rough. The great thing about it is some of the best material is bright red and at the same time clean. Until now, most red and pink tourmaline crystals were horribly included.

History
Tourmaline's name comes from the Sinhalese word "turmali," which probably means "mixed precious stones." Bright, rainbow collections of gemstone varieties were called "turmali" parcels. Sri Lankan (Ceylon) tourmaline was introduced to the European society in the late 1600s or early 1700s by Dutch traders. Similar to rubies which were later discovered to be spinels, numerous red gemstones in the Russian Crown jewels from the 17th century, once thought to be rubies, are actually tourmalines. The Empress Tzu Hsi, the last Empress of China, loved tourmaline and bought large quantities from the Himalaya Mine located near San Diego, California in the early 1900s.

Geology
Tourmaline is 7-71/2 in hardness and does not tend to chip or break. Its luster is glassy and it has a high degree of transparency. Tourmaline is a group that applies to several minerals with similar chemical compositions and atomic structures. Tourmalines belong to the hexagonal crystal systems. Tourmaline crystals begin as colourless and the red is created by trace elements.

Red/Pink colours
Corundum collectors and dealers argue over where to delineate a red ruby vs. a pink sapphire. With tourmaline, the argument is "what is rubellite vs. what is pink tourmaline?" Although the argument will continue, the new find has colours that can be broken down into four groups. The reddest colours have very dark 85-90 tones. Isn’t this always the case with many gemstones? It is almost nature’s trick. These stones are red but black out. Ideally, if you want pure red, choose the reddest stones that black out the least. Approximately 10% of the production is this colour. Generally, the best stones are red/pink with light tones. This open colour is highly desirable. Some say it is reminiscent of Burma ruby. This colour represents the majority of the material. The third colour is fuschia. This is the point in Burma rubies where the stones transition to pink sapphires. These stones have a balance of red and pink and look like pink sapphires. Finally, the last colour is a hot bubblegum pink like hot pink spinel. The last two colours represent 40%, or the balance of the material.

Sizes/Prices
The new material is available from 3mm rounds to stones of 15-20 carats. The largest stone cut so far is about 55 carats. Gemstone collection suites can presently be purchased in this new material. Relatively speaking, the new material is inexpensive. Top one carat sized stones start at $100 per carat. Prices for gem quality red tourmaline can escalate to over $500 per carat for serious large stones.

Treatments
We know today the original crystals were not irradiated or treated. The crystals are so large, they would never fit into a nuclear reactor, a particle accelerator a gamma ray facility. Ditto for heating the material. It doesn’t mean the material might not be heated in the future. However, the new Nigerian material is flying so fast out the door of the owner, they do not have time to monkey with the product.

Conclusion
Some predict the new material may be the next Ouro Fino rubellite. When those stones first hit the market, people immediately recognized the gems would be rare. The same can be said for the new red tourmaline. What makes this find interesting from a collecting standpoint is the goods are an inexpensive red stone compared to ruby and spinel. It might make sense to buy a suite of the various colours or specialize in one colour. If you always wanted to start a gemstone collection and were short on funds, this might be an excellent opportunity. Given the tight economic times, this just may be the right stone at the right time for the right price. Collectors who purchase these goods at the beginning of the market cycle might soon be sitting pretty.

Tourmaline - The modern birthstone for the month of October

There are fourteen different stones listed as birthstones for the calendar month of October, or as Sun/Star, Planetary, or Talismanic stones for the Zodiac sign of Libra or Scorpio. Birthstones for the calendar month of October are opal, tourmaline, jasper, aquamarine, coral, and beryl.

The Zodiac signs of Libra and Scorpio include eight additional stones: peridot, sapphire, lapis, agate, topaz, garnet, ruby, and amethyst.

Tourmaline is the veritable chameleon of the gemstone world. This popular stone is available  in more natural colours and tones than any other gemstone.  In addition to the stones being strongly  dichroic, (a single coloured stone will appear to have two different colours when viewed in different directions), many Tourmalines are actually zoned during grown across the crystal, and  exhibit  two or three colours in a single stone viewed on any axis.

Known for centuries in the Mediterranean countries, Tourmaline really  gained popularity when the Dutch East India Company began to import it into Europe in  the early 17th century from Ceylon. The name Tourmaline was chosen from the Singhalese word Turamali, to assist in the sale of this gem.

Tourmaline is actually the name of a group of related mineral species, although individual species names have been dropped in preference for the "global" terminology "Tourmaline".


What Causes The Colour?

As Tourmalines are part of a related family of mineral species, their basal chemical composition and trace element chemistry determine their colours. In simple terms they are best described as Aluminium Borate Silicates, of changeable composition.  Certain colours had been assigned specific names while others are merely prefixed with a colour before  the word Tourmaline.

Achroite: A colourless to near colourless variety
Dravite: A yellow brown to dark brown variety
Rubellite: Pink to red with or without a violet tint, with deep reds resembling Ruby.
Verdelite: A green variety, found in virtually all shades of green.
Chrome tourmaline: Another green variety, however this differs from Verdelite in that the colour is derived from the inclusion of trace amounts of chromium, resulting in rich Emerald green colours.
Indicolite: A blue variety, again found in almost all shades of blue.
Bi-Colour: Variations, zones and colour bands in Tourmaline are often purposefully accented with the cutting style to show bands and color zones in the gem. Occurring in uncountable colours variations, these are often seen in long acicular crystals.
Watermelon:– Bi-color Tourmalines which show a green skin and a red core
Canary: Bright yellow Tourmaline.
Paraíba: A rare blue-green Tourmaline. The causal element is copper imbibing the stone with an almost neon blue colour
Cat's Eye: Chatoyant Tourmaline in a variety of colors.
Colour - Change: Changes from green in daylight to red in incandescent light.

Other varieties may be simply sold with a color prefix, as in Pink Tourmaline, Green Tourmaline etc.

Purchasing Tourmaline

As with most coloured gemstones  an intense, saturated colour is the most desirable. Again personal preference dictating the colour a buyer will finally choose. In some cases the saturation of the colour can reach such a level that the stones appear almost black, as in some examples of larger Green Tourmaline. These should be avoided.

Tourmaline exhibits strong pleochroism, actually being dichroic, with two distinct colours. In either natural or artificial light these different colours or different shades of one colour  are similarly visible.

Different varieties of tourmaline tend to have differing clarities. Thus while large clean tourmalines in the blue and blue-green colors are common, almost all red and pink tourmalines will show inclusions of some kind. The most common inclusions are needles, fractures and  healed fractures.

While Tourmaline are cut in virtually any cut imaginable, the stones strong pleochroism must be considered. Tourmaline is commonly cut parallel to the longest axis of the rough crystal, in rectangles and rectangular emerald cuts (in both step and princess patterns). In this orientation darker Tourmalines exhibit the lighter of the pleochroic colors, which makes for a more pleasing stone.

Lighter Tourmalines are typically cut across the longest axis of the rough crystal, such that the table in the finished stone is parallel to the shortest axis of the crystal. This ensure that the darker of the pleochroic colours is seen when  the stone is viewed from the top.

Cabochon cut although common tend to be reserved for examples of lower clarity material.

Mineable Deposits
While Tourmaline deposits are found the world over, the most productive mines are found in Sri Lanka, Madagascar and Brazil. Lesser deposits occur in Mozambique, Zaire, Australia, Myanmar, India, Zimbabwe, Namibia, Tanzania, Thailand, Russia and the United States.

Tourmaline beach cliffs in the United States

Common Treatments
The heat treatment of Tourmaline is commonplace. Heating between 450-650 degrees Celsius produces subtle colour changes, which enhance the appearance and value of the stone. Indifferently coloured greens can become rich emerald greens, pale Paraiba and other Blue Tourmalines also benefit from heat treatment to deepen and intensify the colour.

Important & Famous Tourmalines
The Empress Dowager Tz’u His, the last Empress of China, was so taken by Tourmaline that it is rumoured she purchased nearly a ton of it for her personal collation.

The Legend
More of an interesting fact than a legend is Tourmalines ability to become electrically charged. A small electrical current can be induced in the stone, by heating, cooling or applying pressure. All three of these can be achieved by simply rubbing the stones, and accounts for the stone being known as Aschentrekker (Ash Puller) in the days of Meerschaum tobacco pipes.

Taken from Touchstone Gems www.touchstonegems.co.za 
and http://www.bernardine.com

October Birthstone: Opal

Opals come in a variety of colours

Opals are most prized for their unique fiery play of colour, reflecting and refracting light into brilliant flashes of multiple colours. The true source of this play of colour was mistakenly attributed to Adularescence until the invention of the scanning electron microscope. Subsequent  analysis at 20 000 time magnification uncovered the true cause of the effect we know today as Opalescence.

Opal is hydrated silicon dioxide, containing from three to twenty percent water. This feature coupled with its low hardness of 5.5 - 6.5 on the Moh's scale, means that Opals require special care as a gemstone

Colours: Various
Hardness: 5.5 - 6.5
Refractive Index: 1.37 - 1.52
Specific Gravity: 1.98 - 2.50
Crystal System: Amorphous
Enhancements: May be enhanced
Major Sources: Mexico, Australia, Tanzania, Zimbabwe, Brazil

Warnings for Care
Soft, brittle  very susceptible to physical damage / heat

Opal Facts
Opal has a distinguished history dating back to pre Greek, Indian Sanskrit times. The name is derived from  the Indian Sanskrit word for stones  "upala". Three groups of Opal exist, precious opal, fire opals and common opals.

Opal - What Causes the Colour
The body colour or matrix in Opal  can be white, colourless, pale yellow, pale red, brown, gray or black depending on the host rock and the level of impurities.  Internal diffraction of light causes  flashes of any color across the entire spectrum (opalescence). The physical structure of opal is unique, with tiny spheres of silicon dioxide having orientated themselves during the solidification of a mineraloid gel, into pyramid shaped grids interspersed with water molecules.  A combination of the size and spacing of the spheres and tiny natural faults between the grid layout, causes light to be split into its constituent spectrum of colours, which results in the characteristic play of color. While the diffraction and interference can express itself as every colour in the visible spectrum, each Opal is unique in terms of its internal structure and the colours observed. Precious above all other varieties displays multispectral hues that change with the angle of observation.

Precious Opals
Black Opal, is the "King of Opals" which is a precious opal with black matrix color. The high contrast between the matrix and the opalescence ensure this variety has the highest play of colour.  White Opal, is also considered a precious Opal with white or very light matrix colour.

Fire Opals
Fire Opals are names after their orange colour, they do not opalesce and are generally milky or turbid in appearance.

Common Opals
Common Opals are mostly opaque, and devoid of the characteristic play of colour seen in Precious Opals.

Purchasing Opal
When choosing an opal, the lay of colour, matrix color and degree of transparency are the most important criteria which determine the price of precious opals.

While popular Opals are delicate gemstones, prone to dehydration, cracking, scratching and fading. When not being worn it is suggested that they be kept in a humidified environment (60-70%) such as in a plastic bag with a pierce of damp cotton wool, or in a cigar humidor.  For jewellery pieces Opals are better suited for earrings, brooches, and pendants, than rings and bracelets.

Colour
The higher the play of colour and the darker the matrix (for contrast) the more expensive the stones. The exception is Harlequin Opals, where the play of light can be relatively simple but the pattern in important with strong geometrical pattern being sold at a premium

Lighting
Opal looks best viewed in natural especially in the softer early morning or late evening light where the play of colour is maximised.

Clarity
Precious Opal are acceptable in, opaque, transparent or  translucent grades of clarity. The latter are rare and command a price premium

Cut
Mostly round or oval cabochon cut. Fine quality fire opals are facetted, although they are turbid rather than clear.

Mineral Deposits
Historically the main deposits were in Czechoslovakia, however since the early 1900's Australia has been the pre eminent producer of most of the world precious Opal. Currently about  85 percent of the world's supply of white precious opals is mined from the famous deposits at Lightning Ridge, White Cliffs, Coober Peddy and Andamooka.  Other deposits are found in Mexico, Brazil, Guatemala, Honduras, Indonesia, Russia and the United States.

Opal - Common Treatments
Opal are typically impregnated with oils, waxes, or plastics as part  a fracture filling enhancement. This markedly improves the appearance of the stone although over time the effect can be lost, and if the wax or oil decolours then some of the play of colour may be lost.

Important & Famous Opals
There are numerous examples of large Opal in existence, three of the largest ever discovered are, the " Andamooka Desert Flame" (6843kg), Big Ben" (4000 carats), and the "Light of the World" (2250 carats,

Opal - The Legend
According to the Aborigine legends, the creator came down to Earth riding on a rainbow, in order to bring the message of peace to all the mankind. Where his foot touched the ground, the stones became alive and started sparkling in all the colours of the rainbow. That was the birth of the opals.

Taken from:  www.touchstonegems.co.za