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Black Onyx Gemstones - A jet black gemstone

Introduction

Onyx is considered to be a member of the Agate group of Chalcedony gemstones; Chalcedony, on the other hand is a sub species or family of Quartz. Although this is a jet black gemstone, it is still considered as being quite fashionable. Onyx means “veined Gem” and when it is in its natural state, it looks different from other agates in that it has straighter bands of color, which are normally white or black. When Onyx does not have any banding, and the color is purely black, then it is given the name of Black Onyx, and this is due to a process, that is quite old, which dyes the gemstone black.

This is a gemstone that has several colors, even when in its natural state. Onyx that has white and red colors as bands is called Carnelian Onyx, while that with brown and white bands is called Sardonyx. Sardonyx were a favorite of roman soldiers who believed that by engraving the names of famous roman soldiers on talismans made of sardonyx, they could also get the power and courage that these soldiers had. The gemstone is said to sharpen the wits of the wearer, and also remove any negative thinking; instinct and intuition are also sharpened and the wearer changes his or her bad habits and turns them into good.

This is a gemstone that is particularly meant for making cameos because it has different color bands; this means that you can have a cameo made of a dark base, with a lighter stone placed on top. This is a gemstone that is also called Black Magic in some gemological circles.

World leading jewelers such as Chopard, Gucci and Cartier have, over the last 10 years or so, used onyx as part of their jewelry and watch designs. In many of her stunning gemstone designs, Sarah Bennet has used the black stone to create astonishingly striking designs. She says that the deep black luster of the onyx is the perfect background for the most eye-catching designs. Many people agree with Sarah, that the opaque nature of this gemstone gives it one of the best polished lusters that can ever be managed; the only other black stone that may have a better luster is the Swiss Marcasite.

Mesmerizing Black Magic

When it comes to designing jewelry, just as it is in fashion, it is always best to use a black background to make colors look crisp; the best combination is usually black and white. Usually the black background, when designing jewelry, is provided by the onyx, which is deeply black and has a wonderful texture. When making Cameos, they use an onyx stone that has an even black and white later. The white layer is carved so that the design is seen against the black background.

The ancient Greeks and Romans really loved the onyx. Actually the name is derived from the Greek works “onyx” which imply means a claw or nail. This is based on the myth that one day, the frisky love god, Cupid, cut off the celestial fingernails, belonging to Venus, with his arrows as she lay asleep. The story goes on to say that Cupid left the fingernails in the sand, and then the elements and fate turned them into stone so as to protect them from decaying. Although black is not a color that one would want associated with fingernails, but in ancient Greek, all forms of Chalcedony, whether they be white, brown or black, were always called Onyx. However, later on, the Romans narrowed the stones that could be called Onyx to include only those that are black or brown.

As mentioned earlier, the Sardonyx, which has a reddish brown and white banding was very popular with the Romans. It was also used to create seals for letters and official documents because onyx does not stick to wax, and the seals could be mad to resemble fantastic cameos, which would awe all those who set their eyes on the seal. The Roman General known as Publius Cornelius Scipio, who was known for leading his armies to victory, loved wearing Sardonyx, and also asked his soldiers to wear them too, for they made them bold and victorious.

When a jeweler wanted to make a bold backdrop for jewelry, the onyx was always the gemstone of choice. This is a gemstone which has a great texture, and this makes it ideal for texturing; this is why today’s lapidaries love this gem. Onyx has been used as a foil, when making designs from rock crystal, and was also used to enhance the effect of the ‘drop dead red’ of rubies, when they were set in art deco items. It is also popular when used to set off marcasite jewelry which has the yellow metallic luster of gold. If any designer would like to add a little more ‘oomph’ to their jewelry designs, then using the onyx as a backdrop is the way to go.

A profile of Onyx

Today, it has become politically incorrect, in the gemstone world, to say that a particular gem is semi-precious. Today, people prefer to replace this word with the term ‘ornamental’. This is a new term that says that although the stone is very beautiful, its purpose is simply to act as an ornament, but has no real value. This is a word that has been used on many Chalcedony Quartzes, such as the Carnelian, and most of all, the black onyx.

Normally, Black onyx does not cost a lot per carat, and it is only when it is used to make ornate carvings and jewelry, that the price goes up. People say that the untouched stone does not inspire rapture or scholarly study. This is too bad, because today’s jewelers only think that onyx was the main gemstone during the art deco period and is used to enhance today’s jewelry, but what they do not know is that this was a gemstone that was celebrated in earlier centuries and that it has a very rich history, which is full of long periods of adoration.

The grandest and possibly earliest highlight in the history of onyx occurred in about 250 B.C. when a huge onyx, which is thought to have been banded and not uniformly colored, was chosen to be included as the 6th stone, of the 12 stones, which adorned the breastplate of Aaron; this breastplate makes up one of the grandest gem garment in the history of Christianity.

Apart from this honor, the black onyx deserves notation as one of the most popular, and first known, treated gems. The color of the stone was due to a staining method that was recorded in the writings of a Roman soldier and scientists known as Pliny the Elder. He wrote about onyx in his writings named “Natural History”. Actually, one of the nagging mysteries of Quartz is the status of onyx being a treated stone; nobody knows when the term onyx was only reserved to the quartz atones that actually came out as being black naturally, and exclude the agates that had to be treated to get the black tint.

Today, the term onyx brings to mind images of gemstones that had lacquer-like single colors, whether they are black, blue, red or green. However, when the Greeks used the word ‘onycion’, which could be loosely translated to mean ‘Fingernail” they were referring to the stone that is actually black through natural means, and the term remains so to this very day. Later on, the word onycion was shortened to onyx, and it still referred to banded agate stones, which had not been treated. When you look at your fingernail, you may see three distinct bands of alternating light and dark grooves, or bands, running across the cuticle, and these are the ones that led to the stone being given this name.

The question as to whether the Greeks were aware that dyed onyx existed, or did they know that the process of dyeing the stone was started by the romans, arises. If they did, was this staining process, discovered by the Romans, string enough for it to be considered as traditional in the staining of dark stones today? Should this name be reserved for treated, or naturally banded stones?

One thing stands out for sure: In the Victorian Era, the name started being used for nearly all gemstones that had a solid color. Jeanne Bell, a jewelry specialist notes that it was then that the black onyx was given its oddest chapter in its history. It was used as a replacement for any black gem, just like the way the red spinel is used to replace a ruby in the gemstone market today.

The Jet Renaissance

The black onyx gemstone began its final change from a banded gemstone to one of a uniform color, in the middle of the 19th century. It was in this period that the demand for the smooth black stone reached the highest ever recorded level. It is an irony that this demand was driven by the huge demand for a fossilized coal known as black amber, which looked a lot like onyx.

The huge demand for onyx was brought about by an increased demand for black gem and jewelry materials which included vulcanite, which was a form of plastic; glass; jet; gutta-percha, which was a rubber-like resin, among many other black substances. This was because black jewelry was highly priced as a mourning gem, especially during the reign of Queen Victoria, of England, from the year 1837 to 1901; this was during the latter part of the 19th century. When Prince Albert, Victoria’s husband died in 1861, Queen Victoria decided to wear black for the rest of her life, whether it was clothes or jewelry; this led to an explosion in the demand for black gemstones. The expansion in demand was so huge, that the write Diana Scarisbrick, wrote in her book entitled “The Jewelry Design Source Book”, that the manufacture of black jewelry formed its own distinct industry.

The American Civil War, further increased the demand for black mourning articles, and it was at this time that jewelry manufacturers started substituting onyx for jet. In the past, jet was preferable, but because the agate could stain better, and had a higher luster, hardness and durability, it became the preferred gemstone for these articles and jewelry sets. However, the biggest factor behind the huge demand was the fact that agate was easily available, and that it had a lower price when compared to that of jet; the reduction in price and increase in availability was due to a huge increase in the supply of the stones from Brazil, in the year 1821. Natural onyx was available in Europe, especially from the area known as Idar-Oberstein, but the Brazilian variety responded better to the staining process.

At the time, very few people knew that the onyx that was being sold was not always naturally black and that it had been stained. The Germans at Idar-Oberstein, kept this trade secret for a very long time, until a small booklet was released in 1913, which revealed the staining process in detail. Idar-Oberstein had kept the secret ever since it was introduced there in 1819, a period of 94 years.

How the process came to be in the hands of the Germans, is in itself, a fascinating story. The writer Frazier says that a German cutter, known as Johan Jakob Hahn, learned about the process when he was incarcerated in a Debtor’s prison in Paris, with another Italian in the same cell. Another story says that one of the people who took agate to Idar-Oberstein for staining and cutting was incarcerated in the same prison and taught the German about the staining process. However, one must reckon with the fact that, according to Pliny, who has the oldest recorded writings on onyx, also says that the staining process was brought to the Germans by an Italian.

The staining process: carbon coloring

From the year 1813, and all through the mid-century, cutter from Germany uncovered a number of ways in which they could color agates and turn them into a variety of colored stones. They started off by turning white agate to red simply by using heat alone. They then discovered how to turn the stone black, using a method that is known as the sugar-acid process. This process has been summarized by Kurt Nassau in his popular book, ‘gemstone enhancement’; he says that two liquids are used in the process of making black agate. The first one is a solution consisting of 75 grams of sugar dissolved in 1 liter of warm water, making the solution look like honey. The agates are left to marinate in this solution for 2 to 3 weeks, after which they are moved, without being let to dry, into concentrated sulfuric acid; this is a dangerous process and required a lot of care. After they were treated for an hour, and then lied for periods ranging from 15 minutes to 2 hours before being cooled, the agates were then dried using mid-temperatures. The sulfuric acid would remove the water from the sugar in the stone, and the stones would be left with a pure black color, thanks to the carbonated sugar that is left in the stone.

Later on, a new and faster method was found, but this one gave the stones a temporary stain. The method involved immersing and heating the stones in a cobalt solution. However, purists still insist in using the sugar acid methods that was described by Pliny, 200 years ago, since it gave permanent results, even if it takes a much longer time.

The Etymology of onyx

Onyx is a Greek word, which came through Latin, and they both have the same spelling meaning fingernail or claw. The gemstone has a flesh tone color, and it is said to resemble a fingernail. The English term nail is similar to the Greek word.

Varieties – there are varieties in many colors, but the most famous are the red and black onyx.

Onyx has alternating colors which are formed by different layers of Chalcedony. It has a cryptocrystalline structure and this is formed by intergrowths of the silica materials Morganite and Quartz. The bands lie parallel to each other and this is quite different from the chaotic banding that you find in other forms of agate.

Of the variants available, namely Carnelian Onyx and Sardonyx, the latter is significant, both in history and in demand. The red and white bands are more likable than those of the other. The black onyx, however, is the one that is most favored in the jewelry world, although it is rarer than the banded varieties. In the ancient times, there have been treatments that have been used in order to come up with one that is uniformly colored. The treatments can be used to produce the red and yellow variants too; it is interesting to know that most of the black onyx that is found in the market is treated.

Treatments and Imitations

The name onyx has mistakenly been used to label other gemstones which do not belong. Banded calcite from Mexico, Pakistan and other places in the world, which is often in carved and polished form is marketed under the name of onyx. These materials can only be called imitations since they are softer than true onyx, and they are much more available. Today, most of the materials that are carved and sold as onyx are made of this carbonate imitation material. Common Chalcedony and Plain Agates have been used for several centuries to make artificial onyx. According to first-century writer and naturist, Pliny, the techniques were being used by the Romans. The treatment for making colored chalcedony is soaking and boiling of chalcedony in sugar solutions, and then treating the soaked stones in strong acidic solutions which turn the sugar, which has been absorbed in the top layer of the stone into carbon. These are still techniques that are held in high esteem even when other methods, which are faster, are being developed. There has also been the use of nitric acid to remove any undesirable colors, and also to lighten the tint of the stone; such from deep black to gray.

Geographical occurrence of onyx gemstones

This is a well distributed gemstone, which can be found in many places in the world. The most notable are Australia, Brazil, Argentine, Canada, Czech Republic, China, India, Germany, the Unites States of America and The United Kingdom. Natural onyx is found in vesicles of lava.

Historical uses of onyx jewelry stones

In history, onyx was used to make jewelry and adornment that brought about the contrasting colors of the bands. For example, you could get carved figurines in the white layer, which would let the black layer be seen below and this would be a great contrasting story in a sort of reverse silhouette style.

One of the notable carvings are the Gemma Augustea, which was a roman cameo that was deigned between 9 and 12 AD, and is a two layered gem.

Onyx has for a long period been used for making carvings and jewelry; as jewelry, it is used as a cabochon or made into beads. This is a gemstone that has been used to make hard stone cameos, and intaglio engraved gems; the contrasting bands usually make for a very distinct image in the background.

In Egypt, onyx was being used from as early as the second Dynasty, for the crafting of pottery items and bowls. Sardonyx started being used in the Minoan Crete to make items of art, and these were recovered from the archeological digs of Knossos. There are many places in the bible where the onyx is also mentioned. The Ancient Greeks and Romans also used the onyx for mythical and artistic reasons.

Slabs of onyx, from the Atlas Mountains, were used by Mies van der Rohe in the building of the famous Villa Tugendhat at Brno, which was completed in 1930, to create a shimmering wall in the interior, which was semi-translucent.

The onyx is a gemstone that was revered as a classic stone for the making of art items. Any frame made of onyx, would have held a famous portrait for those in positions of power. Even one of the most famous war generals, Scipio, favored this stone. This is a gemstone that should be regarded with the reverence that its history intrinsically gives it. This is a gemstone that should be considered with a lot more respect and adoration than it gets today.



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