Bohemian Garnets

This Brooch Dates From the Third Quarter of the 19th Century. (Photo Courtesy the National Czech & Slovak Museum & Library)

“Bohemian garnets” are garnets mined in an area once known as Bohemia (it often refers to the entire Czech territory, including Moravia and Czech Silesia). They are the variety of garnet called pyrope (from the Greek words pyr for “fire” and ops for “eye”). Those found in Central Bohemia (in the north of the Czech Republic) are considered to be of the highest quality. 
The Bohemian garnet has been mined for over 600 years mostly dug at the mines of Meronitz, and chiefly in the northwestern part of the Czech Republic. The garnets are found in a gravel or conglomerate, resulting from the decomposition of a serpentine. Sometimes, however, they are found in the matrix. When this happens they are often associated with a brown opal. Most of the good quality the stones are small with those as large as approximately 1/4 inch and above being reported rarely. By the 19th century it was determined that the elements creating the intense red color in pyrope were Chromium and Manganese. The color ranges from fiery-red to ruby-red. The Bohemian garnet also possesses excellent clarity, transparency, and has a high refraction of light. This means that the stone has a remarkable sparkle and what has been described as an "inner glow".

The stone gained popularity in Europe in the 18th and 19th century also becoming a favorite of the Victorians. Traditional Bohemian design placed it's emphasis on the arrangement of the garnets, taking precedence over the metal chosen for a piece of jewelry. George Frederick Kunz cites in his book Rings for the Finger Garnet that rings were generally made of faceted, rose or cabochon cut Garnets in 14 or 18 kt gold. By the late 19th century larger Pyropes were typically brilliant-cut, resulting in very bright (red) stones, whereas the very small stones were usually rose-cut. 

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This Art Nouveau Style First Appeared in Individual Creations of Designers Rather Than in Industrial Mass Production. (Photo Courtesy The National Czech & Slovak Museum & Library)

An Example of the Mass Produced Items Typical of the Bohemian Garnet. (Photo Courtesy The National Czech & Slovak Museum & Library)

The introduction of larger scale manufacturing of garnet jewelry created mass-produced machine pressed metal settings and garnets of inferior quality. The majority of readily available "Bohemian Garnet" antique jewelry falls into this mass production category. While these pieces are beautiful in their own right, it should be noted that like any piece of jewelry rarity and individuality are valued much more highly. 

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Antique Pyrope Hairpin From the Smithsonian

Tantalizing Tourmaline

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Tourmaline by Sandy Hoy

October's birthstones are truly spectacular. 
Along with opal, tourmaline is October's birthstone. Both of these stones are gorgeous, but tourmaline is what I want to focus on today. For too long, tourmaline has only been seen as the dull green that is widely available. This is a shame. Tourmaline comes in such a wonderful wide range of colors and with a Mohs hardness of 7 to 7.5, it is durable enough to be used in any type of jewelry.

History
The first tourmaline was recorded in the 1500's in Brazil by a Spanish conquistador. The conquistador confused the vivid green of the tourmaline with that of the emerald. His mistake was not revealed until the 1800's when tourmaline was formally recognized as a distinct mineral species.
The name tourmaline comes from the word toramalli, which means “mixed gems” in Sinhalese (a language of Sri Lanka).  Dutch merchants started using the name to identify the multicolored, water-worn pebbles that miners found in the gem gravels of Ceylon (now Sri Lanka). The stones were brought to Europe in vast amounts by the Dutch East India Company as the demand for gemstones increased. As stated earlier, it was not until the 1800's when scientists were able to positively identify tourmaline as its own mineral species. As with many gemstones until the development of modern mineralogy, a stone's identity was based solely on its coloring, resulting in many stones being misidentified throughout time as ruby, sapphire, emerald, and so forth.

One of the earliest reports of tourmaline in the United States was in California in 1892. In the late 1800s, Tiffany gemologist George F. Kunz worked to make tourmaline an American gem, praising the tourmaline deposits of Maine and California; however, it was not the American market that the tourmaline mines both in the United states and in the Himalayas ended up attracting: it was the Chinese market. 
Because the miners became so dependent on Chinese trade, when the Chinese government collapsed in 1912 the US tourmaline trade collapsed with it. The California mines stopped or moved to sporadic production. Today, mines in San Diego County such as the Stewart Lithia mine at Pala still produce a small supply of gem-quality tourmaline.
The tourmaline trade expanded again during the first half of the twentieth century, when Brazil began to mine large deposits with superb quality. In the 1950s, additional finds were uncovered in other countries around the world, including Madagascar and Afghanistan which have have produced a stunning red tourmaline.

Pink tourmaline from Pala Mountain, Stuart Mine, San Diego. (Photo: Jeff Scovil)

Tourmaline Locations and Mining
Gem and specimen tourmaline is mined chiefly in Brazil and Africa. Additional locations include Sri Lanka, Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, and Malawi. Tourmaline is also sparsely mined in the San Diego County area of California.
Tourmaline (and some other large crystal gemstones) generally occur in an extreme form of igneous rock known as a pegmatite formation. Pegmatite is a type of igneous rock that forms during the last stages of magma cooling. Large crystals are fairly common in many types of igneous rock formations usually due to a slow rate of crystallization. With pegmatites, large crystals are attributed to low-viscosity fluids that allow the chemicals that make up a crystal to be highly mobile on an atomic level.
During the early formation of pegmatites, the magma usually contains a large amount of dissolved water and other chemicals such as chlorine, fluorine and carbon dioxide. Water is not removed during the early magma crystallization, so it becomes more concentrated as the crystallization continues. The presence of the water eventually forms large pockets in the rock. These super heated water filled pockets are also rich in the atoms of various chemicals. Within the pockets, the atoms have a much greater space to expand into than would be present elsewhere. This space combined with the extreme heat allows them to rapidly form into large crystals. The extreme conditions of crystallization in pegmatites have sometimes produced crystals that are several meters in length and weigh over one ton. 

The Colors of Tourmaline
Tourmalines make up a group of closely related mineral species that share the same crystal structure but have different chemical and physical properties. They share the elements silicon, aluminum, and boron, but contain a complex mixture of other elements such as sodium, lithium, calcium, magnesium, manganese, iron, chromium, vanadium, fluorine, and sometimes copper. It is these alterations to a tourmaline's chemical composition that directly influences its physical properties, including color. 

Many tourmaline color varieties have inspired their own trade names:

• Rubellite is a name for pink, red, purplish red, orangy red, or brownish red tourmaline, although some in the trade argue that the term shouldn’t apply to pink tourmaline.
• Indicolite is dark violetish blue, blue, or greenish blue tourmaline.
• Paraíba is an intense violetish blue, greenish blue, or blue tourmaline from the state of Paraíba, Brazil.
• Chrome tourmaline is intense green. In spite of its name, it’s colored mostly by vanadium, the same element that colors many Brazilian and African emeralds.
• Parti-colored tourmaline displays more than one color. One of the most common combinations is green and pink, but many others are possible. Including "watermelon" and Liddicoatite. 

Liddicoatite was first recognized as a separate mineral in 1977. The mineral was named in honor of Richard T. Liddicoat (March 2, 1917 – July 23, 2002), the second president of GIA who is often referred to as the “Father of Modern Gemology.” Most liddicoatite comes from Madagascar, including this slice from the Anjanabonoina pegmatite. Coutresy Harvard Mineralogical Museum, photo by Robert Weldon/GIA

Photo courtesy of GIA

Some tourmalines have a striking cat’s-eye effect called chatoyancy. Cat’s-eye tourmalines are most often green, blue, or pink. The "eye" often has a softer and more diffused than than other stones that display the same effect. This is due to the multitude of thin, tube-like inclusions inside the stone. The inclusions are larger than the inclusions of other stones, such as a cat’s-eye chrysoberyl, so the "eye" isn’t as sharp. Like other cat’s-eye stones, tourmaline needs to be cut as a cabochon to show the effect.

What's in a name? Paraíba Tourmaline

One of the most coveted and expensive of the varieties mentioned above is Paraíba.  It is a relatively "young" gemstone in that it was not discovered until the 1980, but its vivid blues hold the attention of the entire gem world. The reason behind the vivid colors is in fact why a true Paraiba stone is so rare and special. 
Normally, iron, manganese, chrome and vanadium are the elements responsible for the beautiful colors of tourmaline. The Paraíba tourmaline is different: its color is due to copper, an element which had never before been seen in a tourmaline. The presence of copper in the stone is as much what defines the tourmaline as a Paraíba as the location from which it came. Copper in high concentrations is responsible for the coveted radiant blue, turquoise, and green hues. 

Scientists have also (relatively recently) discovered that Paraíba tourmaline may also often contain manganese as well. When both of these two elements are present they produce a variety of vivid colors such as: emerald green, turquoise to sky blue, sapphire blue, indigo, bluish-violet, and purple. They can also result in more muted pale grey to violet-blue tones. 
Because of the stone's high value in an uncut state, Paraíba tourmalines are almost always custom cut to retain as much of the stones weight as possible, however the stones are still in sizes bigger than one carat. 

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The flawless 191.87 carats Paraiba tourmaline, The Guinness World Records largest, has been placed by experts in the field amongst the world’s rarest gems.

Recently scientists have discovered that Paraíba tourmaline often also contain manganese and it is the interplay between these two elements that creates the coveted colors. 

Since the late 1980s, the Paraíba area of Brazil has been a source of a strikingly colored variety of tourmaline called Paraíba tourmalines.

With Paraíba, the key factor is not size, but color; all factors being equal, the stone with the better color is a better choice.
During Paraíba tourmaline’s brief history, the gem has always been extremely scarce. However, new discoveries of copper-bearing tourmalines that resemble the vibrant, intense colors of the gems found in Brazil’s Paraíba region have also been found in other parts of the world. An article in the Spring 2008 issue of GIA’s Gems & Gemology scientific journal described copper-bearing gems present in Mozambique. Nigeria has become a source of these striking gems as well. With these new sources there comes the possibility that viable, commercial sources of this rare copper-bearing tourmaline might provide a larger supply of material. This brings a new problem for the niche Paraiba trade. If the stones of the same chemical composition and quality are being found outside of Paraiba does the trade name still apply? Only time and the market will tell. I personally think that the romance of a trade name should have little to do with the stone you are buying. The romance of a trade name aside, if the quality is good and the color is vibrant then that is what we should judge a stone by. 

The Lily Safra poppy flower brooch with diamond and tourmalines sold for $1,273,320 at Christie's Geneva, 5/14/2012. - © Christie's Images/The Bridgeman Art Library

The rainbow of colors that tourmaline has to offer the wearing is truly impressive. This stone has something to offer for everyone.  

September Sapphires

Sapphire and diamond "Copacabana" ring by Chopard

Welcome to beautiful Sapphire September! (I am a bit biased about this stone because it is my birthstone)
Sapphire is a variety of corundum. It is an oxide mineral and is a 9.0 on the Mohs hardness scale. It is an excellent for any type of jewelry. 
The name Sapphire comes from the Greek word sappheiros meaning ‘blue stone’.  But sapphires are not just blue, they come in every color of the rainbow except red. Red corundum is called Ruby. 
Trace elements such as iron, titanium, chromium, copper, or magnesium can give corundum a blue, yellow, purple, pink, orange, or green color.

Beautiful rare velvety purple 8.00ct sapphire in a platinum setting with diamond accents by  Robert Procop.

Diamond and Golden sapphire necklace by Van Cleef & Arpels

Peridot

The largest cut peridot olivine is a 310 carat specimen in the Smithsonian Museum in Washington, D.C. Photo courtesy of the Smithsonian Museum

Welcome to August and a very happy birthday to all of the August babies out there! You have two great birthstones peridot and sardonyx. Here is a little about peridot.
Peridot is gem-quality olivine. Olivine is a silicate mineral and has a mohs hardness of 6.5-7. This is almost smacked dab in the middle of this hardness scale so don’t be afraid to wear it in any type of jewelry. 
Olivine in general is a very abundant mineral, but gem quality peridot is rather rare. Peridot olivine is mined in Arkansas, Arizona on the San Carlos Reservation, Hawaii, Nevada, and New Mexico at Kilbourne Hole, in the US; and in Australia, Brazil, China, Egypt, Kenya, Mexico, Myanmar (Burma), Norway, Pakistan, Saudi Arabia, South Africa, Sri Lanka, and Tanzania.
Peridot ranges in color from yellow, to yellow-green, olive-green, to brownish, sometimes a lime-green, to emerald-ish hue.

Photo courtesy of Bonhams

This late 19th century peridot necklace, was sold by Bonhams Auction House in 2011.

Zircon

We are marking the end of the year with another of December’s birthstones: Zircon

In the past when many people heard the word “zircon” (a naturally occurring gemstone) they immediately jumped to something more familiar, “cubic zirconia” (a man-made diamond simulant). In the current market, consumers have become more savvy in understanding that there is a difference; however, even though many people may have heard of zircon very few have ever encountered it.

Red Zircon Crystal, Kunar Prov., Afghanistan Photo courtesy of http://www.marinmineral.com/

Some gemologists classify zircons into three types—high, intermediate, and low.
The majority of zircon is generally of the low and intermediate variety. This is directly related to the chemical makeup of zircon. Zircon a zirconium silicate containing trace amounts of the radioactive minerals hafnium, uranium and thorium. Over time, these radioactive components can break down and destroy the internal lattice of the crystal (over tens of thousands of years). This leaves the zircon with an amorphous structure that has a pithy appearance. “Intermediate” zircon is also exposed to the damaging effects of radiation but to a lesser extent than low zircon.
Virtually all zircon that is used in jewelry is of the “high” variety. Zircon that is of the “high” variety is geologically “young” and virtually unaffected by radioactivity. These high zircons have full crystal structures and as a result, they have the normal physical and optical properties which are compatible with faceting. "High" zircon can also be heat treated to create colorless, blue or golden stones.

The many colors of Zircon Photo courtesy of GIA

The stone comes in a beautiful array of colors including warm browns and lovely shades of cinnamon, sherry, yellows, oranges, and reds. The most well known of the colors are the vibrant bright blues (which may be enhanced by heat treatment). It has been estimated that approximately 80% of all zircons sold are blue, and usually command a slightly higher price. Blue topaz is often offered as a less expensive alternative.
In the early 1900s zircon was often used as a diamond simulant. Due to its doubly refractive nature, zircon displays a high amount of “fire”, even greater than that of diamond, adding to the appeal of the stone. As new technology emerged it was replaced with more convincing look-alikes including many imitations, and it’s name still brings to mind the word “imitation today”. This is sad because zircon is a beautiful stone with a wide range of colors and its own charming history and lore.  

Zircon Ring ca.1850 Photo Courtesy of the Victoria and Albert Museum

"Many scholars think the stone’s name comes from the Arabic word zarkun, meaning 'cinnabar' or 'vermilion.' Others believe the source is the Persian word zargun, or 'gold colored.'  Considering zircon’s color range, either derivation seems possible.” (GIA).
In the Middle Ages, zircon was believed to aid in sleep, keep away evil spirits, and promote riches, honor, and wisdom. 

Cat's-eye Zircon Photo courtesy of GIA

 
Blue zircon especially was a favorite of the Victorian Age. Zircons are usually relatively free of inclusions, but many untreated zircons may have a cloudy or smoky appearance. If it’s very noticeable, this can negatively affect price. In Victorian times, this smokiness made zircon a popular gem for mourning jewelry.
The majority of modern zircon that is used in jewelry will not have eye visible (visible to the naked eye) inclusions.  Long, parallel, visible inclusions can make the stone desirable when it is cut into a cabochon because it may create the cat’s-eye effect.

It’s a challenge to cut zircon because the gem is brittle. Cutters usually fashion zircon in the brilliant style to take advantage of its luster and fire. In the past, cutters developed a modification of the brilliant cut, known as the “zircon cut,” which uses eight extra facets around the pavilion (the gem's lower portion). In modern times this is rarely seen, as the added labor required makes it not cost effective. Zircon can also be found in step cuts (rows of parallel facets), and mixed cuts (a combination of brilliant and step-cuts). 

The fact that the gemstone has been passed over for so long is an absolute shame. Gemologist and author/researcher George Kunz (a famed gemstone buyer for Tiffany & Company) attempted to rename the stone “starlite”, owing to zircon’s high fire, to promote the gemstone. However, the name failed to catch on and over time the stone seemed to fall by the wayside. There may be a potential upside to the relative obscurity of zircon though. Analysts in the gem industry have stated that zircon has yet to reach its full potential in value, and it will only appreciate in value so it may be an excellent time to branch out and embrace the beauty of zircon.

The final word:
Zircon is Not Cubic Zirconia! Zircon is a naturally occurring mineral found in the earth. Cubic zirconia is a man-made diamond simulant. They have both been used in place of diamonds, though cubic zirconia is used much more commonly than zircon in modern times. The differences are easy for a trained gemologist to spot. When in doubt ask an independent gemologist.

Basic Information:
Formula: ZrSO4, May contain minor U, Th, Pb, Hf, Y/REE, P and others.
Crystal Systems: Tetragonal
Hardness: 7-1/2
Color: Yellow, Clear, Blue, Pink, Brown...etc
Lustre: Adamantine, Vitreous, Greasy
Mineral Group: Zircon
Major sources: Major sources of zircon are the Chanthaburi area of Thailand, the Palin area of Cambodia, and the southern part of Vietnam. 
Misc: Eye visible, strong double refractivity. This causes high fire that is more noticeable in light colored stones but may be seen even in darker stones. 

Turquoise: The Desert Beauty

A turquoise and gold ring which once belonged to Jane Austen Sold by Sothebys

The most traditional birthstone for the month of December is Turquoise and  the zodiacal stone for Sagittarius. Opaque, varied blue colors that has been used for centuries in jewelry and in decorative ornaments.

If cold December gave you birth,
The month of snow and ice and mirth,
Place on your hand a turquoise blue;
Success will bless whate'er you do.

Turquoise is found in various locations around world that all share the same characteristics: dry, arid, barren and possessing acidic, copper-rich ground water. This ground water creeps downward it reacts with other minerals. The product of this process is the compound of hydrated copper and aluminium phosphate known as turquoise.

The deposits of turquoise usually form in iron-rich limonite or sandstone. The remnants of these host minerals (called the matrix) are what leave the veins or splotches on the turquoise. (Limonite creates the darks brown markings and the sandstone creates tan markings)
The texture of turquoise is a result of both its structure and composition. If you look at turquoise under a microscope you may see that it is actually an aggregate of microscopic crystals that form a solid mass. The closer the crystals are packed, the finer the texture and the less porous the material. Fine textured turquoise has a shiny waxy luster when it is polished, while less dense turquoise results in a duller luster.

Turquoise from Bisbee Arizona

The porosity also affects the stones' durability with the less porous turquoise possessing less toughness. Because of the decreased visual appeal and the lesser amount of durability more porous turquoise is often treated to make it smoother, shinier, and more marketable.

                                                                                                                                                                                  Most people will be familiar with vein like black matrix running through the vibrant blues or greens; however, the most expensive and prized turquoise has no matrix showing. The second most valuable is a thin web like matrix that is evenly distributed throughout the stone.This really is personal preference, and some turquoise lovers may find imperfections part of the charm.

Turquoise is very soft, ranking a 5-6 on the Mohs hardness scale. This makes the stone ideal for carving and artists throughout history in Europe, Asia, the Middle East and  the Americas have utilized it as a medium for both jewelry and art objects.

Turquoise has a long and varied history (that continues to this day) of being used as talismans, amulets, or religious artifacts as it has been attributed to have special power and meaning to various cultures. The ancient Egyptians, Meso-Americans, Native Americans and Tibetans have believed in the special powers of turquoise for centuries. Some believed that turquoise can protect its wearer from harm, others thought that it brought good luck or longevity, and some uses and meaning have been lost to history.

                  Egyptian middle Kingdom faiance hippo
                                       The MET Museum

The high value placed on fine turquoise caused many imitations to be made. The first of which dates back to ancient Egypt: a glazed earthenware material called faience. Later glass, and enamel were used. In modern times plastic, porcelain, composites of minerals were used. In 1972 the closest “synthetic” turquoise was produced by Pierre Gilson. I put synthetic in quotes since it is actually called a simulant owing to its chemical composition differing from actual turquoise due to a bonding agent. The simulated turquoise is available in both fine and spiderwebbed varieties.

The most common natural stone imitators of turquoise that might be encountered are dyed howlite and magnesite. These stones are both white in their natural state and contain black veining.

All of these imitators are fairly easy to identify by a  trained gemologist and many can be identified by the general consumer as well.

Basics:
Chemical Formula: CuAl6(PO4)4(OH)8•4H2O Copper containing basic aluminium phosphate
Hardness: 5 to 6 on the Mohs scale
Formation:Turquoise occurs as botyroidal (grape-like) masses or nodules in fissures.
Found in: Currently the finest quality turquoise is found in Northeast Iran. Major turquoise deposits are also found in Afghanistan, Argentina, Australia, Brazil, China, Israel, Mexico, Tanzania and the USA.