The Colorful World of Topaz

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I have always thought it was a shame that the general public has been forced into the misconception that topaz is merely and inexpensive blue gem. Incidentally the blue color is hardly ever natural: It’s almost always caused by treatment. Topaz has a far broader and more colorful story to tell gemstone lovers. 

Topaz is allochromatic. This means that the color you see is caused by an elemental impurity or defect in its crystal structure rather than by an element of its basic chemical composition. For example, the presence of the element chromium causes natural pink, red, and violet-to-purple colors in topaz. Imperfections at the atomic level in topaz crystal structure can cause yellow, brown, and blue color. Brown is a common topaz color, and the gem is sometimes mistakenly called “smoky quart

THE 97.45-CARAT BLAZE IMPERIAL TOPAZ IS IN THE COLLECTION OF THE FIELD MUSEUM OF NATURAL HISTORY. - (PHOTO: "GEMS AND GEMSTONES: TIMELESS NATURAL BEAUTY OF THE MINERAL WORLD" BY GRANDE & AUGUSTYN, U OF CHICAGO PRESS.)

Topaz actually has an exceptionally wide color range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and purple. Colorless topaz is plentiful, and (as was mentioned earlier) is often treated to give it a blue color.
The color varieties are often identified simply by hue name—blue topaz, pink topaz, and so forth—but there are also a couple of special trade names. Imperial topaz is a medium reddish orange to orange-red. This is one of the gem’s most expensive colors. Sherry topaz—named after the sherry wine—is a yellowish brown or brownish yellow to orange. You may hear stones in this color range are referred to as "precious topaz". This term is used to distinguish them from less expensive citrine (yellow quartz) and smoky quartz.

 

TOPAZ CRYSTALS ARE TYPICALLY ELONGATED, WITH GROOVES PARALLEL TO THEIR LENGTHS. FOR THIS REASON, THEY'RE COMMONLY CUT INTO LONG OVAL OR PEAR SHAPES. THESE CRYSTALS SHOW ORANGE, PINK, AND BROWN COLORS. - ERIC WELCH/GIA

What is Imperial Topaz?

Red is one of the most prized and rare topaz colors. Red represents less than one-half of 1 percent of facet-grade material found. The color known in the gem the trade as "imperial topaz" is even more highly prized and rare. They color is a bit elusive and subjective; however, many dealers insist that a stone must show a reddish pleochroic color to be called imperial topaz. The reddish pleochroic color often appears at the ends of fashioned gems—like pears and ovals—that have an otherwise yellow-to-orange bodycolor. This look is illustrated in the images below. 
The name for "imperial topaz" originated in nineteenth-century Russia. At the time, the Ural Mountains were topaz’s leading source, and the pink gemstone mined there was named to honor the Russian czar. Ownership of the gem was restricted to the royal family.

THIS UNTREATED 45-CARAT IMPERIAL TOPAZ DISPLAYS AN ATTRACTIVE REDDISH PEACH COLOR. (PHOTO: CONSTANTIN WILD, IDAR-OBERSTEIN)

SPECTACULAR PRIZE-WINNING, ORANGY-RED, FLAME-SHAPED IMPERIAL TOPAZ GEM. (PHOTO: GEM COURTESY OF JOHN DYER & CO.)

Bohemian Garnets

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

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. 

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)

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. 

Antique Pyrope Hairpin From the Smithsonian


Peridot

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

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

Photo courtesy of Bonhams

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

Zircon

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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/

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 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

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

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.