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Rarest of the Rare: Unique Gemstones of the World

Alexandrite Mineral
Alexandrite (variety of chrysoberyl)

In all the naturally occurring substances, gemstones catch our attention the most. Due to their color, shapes, sizes and textures, gemstones are intrinsically rare and always an eyecatcher. And among all the elite and rare stone types, there are some which are considered as the rarest due to their scarcity of nature.

Let’s find out some details about these gemstones that are the rarest of the rare.

Alexandrite: Emerald by Day, Ruby by Night

Named after the Russian tsar Alexander-II, Alexandrite belongs to the family of Chrysoberyl family. It was first found in the Ural Mountain range in Russia in early 18th century. Due to some digression from Chrysoberyl minerals, it became one of the rarest gemstones on the face of the earth. Alexandrite is famous for exhibiting hues of emerald and ruby when seen in the presence of light and darkness respectively.

When it shines under different light sources, it appears with different shades of green, magenta and blue which clearly indicate that Alexandrite possesses splendid color features. The impurities of iron, titanium and chromium are supposed to be the reason why it stands alone among all the other Chrysoberyl gemstones.

Tanzanite: A Gift from Foothills of Mount Kilimanjaro 

This gemstone belongs to the family of zoisite gemstones with blue color. The rarity of this stone can be understood by the fact that the only known deposit of this stone is found in the foothills of Mount Kilimanjaro in Northern Tanzania. Therefore, this zoisite gem is even named after the country.

The bluish-purple stones are found and mined in decades, and therefore it is considered rarer than diamonds. Tanzanite also exhibits different hues under different crystal orientations and light conditions.

Red Diamonds: A Rare Tale of Romance

The combination of red color and diamond stone can be the ultimate gesture of love. Red diamonds are considered to be the fanciest and rarest diamonds. Unlike other fancy diamonds which get their color from different impurities, diamonds get red hue due to a rare bend in its atomic structure known as plastic deformation. There are very few red diamonds in the world (some estimates suggest that only 30 diamonds exist with such color formation).

Grandidierite: Madagascar’s Another Natural Offering

Grandidierites are extremely rare gemstones only found in very few places such as Madagascar, Sri Lanka and Namibia. They were first discovered in Madagascar in the early 19th century by a French mineralogist and named after Alfred Grandidier who is thought to be the first authority on the natural history of the region.

Grandidierite comes in bluish green color patterns, shades which come from the tinge of iron impurities in it. They come in orthorhombic crystal structures. The typical rare Grandidierite appears completely transparent.

Poudretteite: An Exquisite Pink Gem

Poudretteite was first discovered in Canada and named after the family which operates the quarry from which this stone was discovered. Even after more than 50 years, it can only be found in two locations in Canada and Myanmar which makes this gemstone incredibly rare.

The color of Poudretteite depends on the optical phenomenon in which different the color appears when observed at different angles. However, Poudretteite shows light pink and purple hues mostly. Manganese is the color giving element present in Poudretteite, so the color saturation depends on the amount of Manganese present in the stone’s crystal structure.

Benitoite:  A Californian Rarity

Benitoite is a rare gemstone that is extracted from the only and limited deposit near San Benito River in California. It was discovered in 1907. Benitoite comes in blue and purple shades and glows like blue chalk when put under UV light.

Due to its unavailability, Benitoite is not used as a typical gemstone in jewelry items. It is almost impossible to find in the open market and is usually part of rare gem collections.

Musgravite: Distinctive among all the Taaffeite

Musgravite is a rare oxide gemstone belonging to the family of Taaffeite gemstones. Musgravite was first discovered in the Musgrave Range of South Australia. It is very difficult to differentiate them from all the other Taaffeite stones and only an expert can do this. Musgravite exists in grey, mauve, grey purple and light olive green shades.

Emeralds: A Part of Ancient Religious and Cultural History of The World

red diamond 3d rendering
Red Diamond Emerald

Since ancient times, the Emerald has caught the interest and fascination of humans. Like many other gifts of nature found in lush green shades, real emeralds are also found in stunning green color. There are other green gems such as peridot and tourmaline but none are as famous, beautiful and rightfully expensive as emeralds. In this article, we will try to shed some light on the historical significance of the stone. Let’s start with its name origin and some ancient history.   

Emerald’s name origin

Historians are agreed on the fact that the word ‘Emerald’ is the distorted form of a Greek word ‘smaragdus’ which means ‘green’.

Trace back of emerald in the history

The first mining of emerald was reported in the ancient Egypt dating back to 300 BC. In Egypt, emerald was revered as a precious gemstone.  Cleopatra, the last ruler of Ptolemaic Egypt considered the manifestation of beauty, was fond of emerald and it is used as part of many of her royal adornments.

History also suggests that Roman were also fond of this magnificent gemstone. According to the writings of famous Roman naturalist Pliny the Elder, in ancient Rome people stared into emerald to relieve tediousness and exhaustion.  

In the following discussion, we will try to look into the importance of emerald in different cultural and religious symbolism.

Emerald: Equally loved by ancient gods

In many religious beliefs, offering emerald to the spiritual deity results in different rewards for the people. For instance, Hindus were the belief that people who offer emerald to the god Krishna become high in heaven and god rewards these generous offerings with the knowledge of soul and eternity.

There is another historical trace of people offering emeralds to their gods.  A Spanish historian from the 16th century AD, who had extensively researched on the north of South America, also hinted about the emerald offering of the natives to their gods. According to him, people used to burn emeralds and gold before the depictions of the Moon and Sun which are considered the highest divinities.

Emerald used as a rewarding gift to gods implies that not only humans but gods were also fond of this gemstone.

 

Emerald: A stone embedded in the breastplate of Aaron

The breastplate of Aaron, which is discussed in the Old Testament, had different gemstones embedded in it. Scholars are still debating the type of those gemstones because revision to the original text has changed the names and categorization of the stones. Apart from that, the linguistic changes through the course of time have also altered the names of different gemstones.

It has been cited that a greenstone was used in the breastplate of Aaron. It could be the real green emerald, green feldspar or any other green stone but historical indications are stronger towards the use of emerald. Emerald began to be mined near the ancient site of Nubia, Egypt before the era in which the breastplate got made.

The Peruvian goddess made of emerald

In the 15th century, when Spanish kingdom was roaring around the South America, people of the city of Manta in present-day Peru used to worship a goddess named Umina. The goddess was made of an emerald of the size of an ostrich egg. It was displayed to the public only on feast days by the priest.

According to their dogmatic belief, followers can worship the goddess by only bringing her daughters. Small size emeralds were called the daughters of the Umina. When the city was captured and conquered by the Spaniards, they found plenty of emeralds there however they failed to trace the emerald goddess Umina.

Spaniards also waste many of these precious gemstones in order to determine their originality. They smashed emeralds on anvil because they were of the thought that original emerald is the hardest gemstones and it can withstand this smashing.

Emerald Symbolism embedded in depiction of mystic and mysterious cities

There are many tales and folklore in India which talks about the mysterious cities and forts with walls, facets and entire temples made of gold and other precious elements. There are paintings which depict these cities and their features. According to the pictorial depictions of those wealthy cities, leaves of plants and trees have dripping emeralds and rubies.  

From the above discussion, it is quite clear that emerald has always been an important part of different historical religious and cultural reference spread all across the world.

 

Corundum – Parent Mineral of Ruby and Sapphire


Corundum Mineral Stone
Photo by Epitaviyayimages.com

Corundum is a mineral found in many metamorphic, sedimentary and igneous rocks. It is aluminum- based rock-forming mineral. Pure corundum ore exists in colorless form. The mineral gets its color majorly from iron and chromium impurities. Some other mineral impurities such as cobalt, nickel and vanadium can also be found in the deposits of corundum. The mineral is known to possess high levels of hardness, therefore, it can easily be found in crystalline form in many different colors.

Even though corundum has been used by humans in different shapes and forms for centuries, the revolution in modern mining history of corundum happened when a geologist W.F. Ferrier pointed to the large deposits of corundum in Canada in his survey report in 1896. In a few years, the mining of corundum started in the communities of Ontario, Hastings colony and Carlow. Now corundum, both in natural and synthetic form is used for many purposes.

People know corundum by sapphires and rubies

People are familiar with this mineral through the gemstones of ruby and sapphires. Both of these precious stones are the variants of corundum. Finer grades of corundum in red hues are called rubies while the ones with blue shades are known as sapphires.

Physical properties of corundum

Corundum comes in the top three hardest minerals along with moissanite and diamond.  It is assigned with that hardness of 9 on Mohs scale. They get recognized by their distinctive physical properties. They possess high specific gravity and definite hexagonal crystalline structure. They also have a great tendency to cleave along stressed areas.

History associated with the name ‘Corundum’

Most historians agree to the fact that the word ‘Corundum’ is derived from the Sanskrit word korund or Kurundum. Another fable associates the name with an ancient district of Karund in the state of Orissa, India. The deity of the region is Manikeswari, which literally means ‘goddess of rubies or corundum’.  This claim was also substantiated by the fact that the karund district was known for the deposits of ruby gemstone.

Occurrence of corundum in the nature

Corundum can be found in many different geological settings and in all those rocks that are rich in aluminous instead of silica. Syenite, nepheline syenite and pegmatite, all of these igneous rocks contain corundum as their primary mineral. It is also found in metamorphic rocks derived from aluminous and carbonate sediments. Marble, schist and other products of regional metamorphism also contain corundum.

Some of the naturally occurring marble deposits contain gem-quality of vibrant colors and clarity. Due to its relatively inert nature and hardness, it is able to survive the extremes of weather and can be found in different alluvial deposits. Most of the higher grade corundum is obtained from the clay beds of different river deltas.  Word’s famous alluvial deposits of corundum are located in Cambodia, Sri Lanka, Afghanistan and India.

Corundum hardness: best suited for abrasives

The hardness of corundum makes it the best contender for abrasives for many industrial uses. Corundum is first crushed into smaller particles which are then processed to produce same-sized granules. The final product is used in different ways for the purpose of abrasion. It is used to make polishes, sandpapers, grinding wheels and other grinding media.

However, with more innovation and precision in the manufacturing process, some disadvantages of natural corundum started to appear. The particles of corundum are usually small and irregular in their sizes – this means the quality needed in the making of many products is not necessarily met.

Synthetic corundum on the other hand has consistent physical properties. It is made of calcined bauxite. Corundum in the form of emery rock has also been used as an abrasive in many industries. It is a granular rock rich in corundum, spinel, magnetite and hematite.

Corundum as a gemstone

Even though the use of corundum as an abrasive has declined in recent years due to the availability of better options, no one can take the place of corundum in the world of gem and jewelry because two of the ‘big four’ minerals are variants of corundum.

Diamond, ruby, sapphire and emerald due to their historical significance and aesthetic appeal are the four most sought-after gemstones in the world.

Formation of Gemstones

Valuable gemstones are extracted from the earth’s core and include mineral rocks, diamonds and stones in a variety of colors;, for example, rubies, emeralds and sapphires. While the diamond is still the world’s most precious and well-sought after stone among all, we can see a rise in demand for various other gemstones as well. Not that they were not valued any time before, but in recent times, people have shifted their interests towards gemstones other than diamond, and in fact, most of the engagement and wedding rings now hold a semi precious gemstone in center.  However, just as their demand and value has been on the rise, so is the need to authenticate their originality.

Almost all gemstones are found in the crust of earth. However, there are two which are found deep below in earth’s mantle: Peridot and diamond. There are kimberlitic pipes below the earth which is the main passage for diamonds to surface up. Through these pipes, molten magma flows and as it reaches the surface, it collects foreign rocks known as xenoliths on its passage. Diamond is one of the rocks, which are assimilated on the way and brought up the surface through volcanic eruptions.

Igneous rocks

Igneous rocks are those that are formed when the molten magma beneath the earth cools down and starts to crystallize. Igneous rocks include two further types further: intrusive, which are formed beneath the surface when the magma cools down, and extrusive, which are formed when lava cools down above the surface of earth.

At the time of cooling, there are many minerals present which starts to combine and form a crystallized structure. This is how gemstones are formed. Environment, cooling time, pressure, temperature – all these factors play an important role in forming each of the gemstone. Larger gemstones will be formed if the cooling process is slower. Diamonds, spinel, Peridot, quartz, moonstone, topaz, tourmaline, zircon, citrine, and amethyst – these all are the most common types of igneous rocks.

Sedimentary cycle

Sedimentary cycle is the second most important process in the rock formation. Rocks formed through this cycle are not actually formed, but rather found. Due to the process of weathering over the time, many rocks are washed down with rain, wind and river and deposited into the sea or riverbanks. There, they keep accumulating along with other organic and inorganic material mixing into it, such as plants, mud, shells. As the time passes, these mixtures are compressed and compacted to form hard rocks. Most of the time, those rocks will be found in sedimentary rocks that have been originally weathered from their parent rocks, which then can be igneous or metamorphic in nature. Common rock minerals found in these sedimentary deposits include Beryl, Opal, Turquoise, Malachite, Azurite, Chrysoprase, Chrysocolla.

Third source of gemstones are the metamorphic rocks. As the name suggests, these rocks are formed when already existing rocks goes through a change process due to pressure changes or changes in temperature. The process is called recrystallization, since during this process, molecular structure of these rocks is broken down and restructured, forming a completely new rock, with same basic composition but different structure. Some of the common metamorphic rocks are garnet, tanzanite, sapphire, ruby, kyanite and emerald.

Top Five Largest Diamonds in the World

“Diamonds” by whatleydude is licensed under CC BY 2.0

What is it that we have not seen or heard about diamonds? From being a girl’s best friend to a creating a political fiasco, diamonds never fail to be the center of attention. They have potential to capture anyone’s eye; especially the bigger stones.  People are still fascinated by diamonds as they were in ancient times. Promising strength due to their non-breakable nature, diamonds are also a symbol of love and commitment.

When it comes to diamonds, size is a huge attraction and increases the value of the stone. Here is a list of the top 5 largest diamonds in the world.

Sergio

Weighing 3167 carats, Sergio is the largest rough diamond in the world. It was discovered from Brazil in the year 1893 and is one of the rare black diamonds that still have scientists debating about the origin of this category of the stone. It has mythical stories attached to it and is thought to hail from meteoric origins; but regardless of anything being said, Sergio enjoys the title of being the largest diamond of the world.

The Cullinan

The Cullinan weights a magnificent 3106.75 Carats and ranks second in the list of the largest diamonds in the world. It is famous around the world due to numerous reasons. Weighing 1.37 lbs when discovered, it made a striking gift for Edward II, the then King of United Kingdom. Later on, the Cullinan was taken to Amsterdam where it was cut into 9 large and as many as 96 small gems. Today, it values to be an estimated $2 million.

Excelsior Diamond

Excelsior Diamond had the honor of being the largest diamond of the world until 1905, when The Cullinan was discovered. It was founded in the year 1893 in Jagers Fontein Mine. Later on it was cut into 10 stones with the largest one weighing 69.68 carats. It is a beautifully stunning white diamond that reflects a hint of blue as well.

Star of Sierra Leone

Discovered in 1972, this beautiful stone made it to the hands of Harry Winston, a famous American jeweler. Since it was in rough form, this magnificent diamond was cut into 17 smaller gems, some of which were used to craft the famous Star of Sierra Leone brooch.

Incomparable Diamond

Incomparable weighs 890 carats and is a discovery of 1989. Found in Congolese by a young girl, it was years until experts cut the magnificent stone into smaller gems. The final result was a uniquely triangular shaped diamond in the shade of yellow and brown. Most recently, it was up for auction on Ebay in 2002. Surprisingly, no one bought this beautiful piece.

Gemstones have high value due to their size, shape, color, cut, and weight. In case of diamonds, it enjoys a very special status that has a abstract meaning and worth as well.

Four Cs of Diamond Grading

The Gemological Institute of America (GIA) was the first to implement a universal diamond grading system. Before 1953, there was no agreed upon standard for judging diamonds. The founder of GIA, Robert M. Shipley, created the Four C’s grading system in 1953 which became the international standard for determining diamond quality. The Four C’s stand for color, clarity, cut, and carat weight.

Color

Gem-quality diamond color evaluation is based on a lack of color. The most perfect diamond is colorless and has no hue. The scale of color starts with D, the rarest, and continues on to the letter Z. Many of these color differences are extremely subtle and are not seen by the untrained eye. However, these differences can be quite big when it comes to a diamond’s quality and price. Excellent value diamonds have a color grade of D, E, F, G, and H. These are also best set in platinum or white gold.

Clarity

Diamonds are a result of carbon being exposed to intense heat and pressure under the earth’s mantle for over a billion years. This long process can add internal and external imperfections called inclusions and blemishes, respectively. The number, size, nature, and position of these imperfections affects the clarity of the stone. The clarity scale has six categories: flawless (FL), internally flawless (IF), very, very slightly included (VVS1 and VVS2), very slightly included (VS1 and VS2), slightly included (SI1 and SI2) and included (I1, I2, and I3). FL diamonds account for less than 1% of the current diamond supply while it accounts for less than 3%, these are the highest valued diamonds.

Cut

The cut refers to proportions, and not shape. Diamonds are the only naturally occurring gemstone with a refractive index greater than 2, meaning they are very sparkly, this sparkle is called fire in the gem industry. A diamond’s cut will affect its fire, brightness, and scintillation. The cut scale contains five grades: excellent, very good, good, fair, and poor. An excellent cut allows light to enter the stone and disperse it properly throughout the diamond, reflecting back through the top. When a diamond’s cut is too shallow or too deep, the light can escape through the bottom of the stone.

Carat

Many think that a diamond carat refers to size, when it actually refers to weight. As carat weight increases, so does the rarity and price of a diamond. A metric carat is defined as 200 mg. Each carat can be divided into 100 points. This allows precise measurement to the hundredth decimal place. A 25 point diamond weighs 0.25 carats. Many times, a diamond can look bigger but be a lower carat based on shape and size. Since prices are based on carat, one can usually get a better deal for a diamond that ends in .9 carats. A 2.9 carat stone can look bigger than a 3 carat stone and cost less, simply based on size.