Alexandrite Appraisal

As a leader in natural mined Alexandrite, we receive many emails and phone calls from people looking for an Alexandrite appraisal on a gemstone or piece of Alexandrite jewelry sight unseen. After a brief explanation of what a proper appraisal entails, undoubtedly, the next request is for a ‘guestimate’ of their stone’s value followed by a number of IFs. “If my Alexandrite is X carats, and if its color changes from Y to Z, and if… What is it worth?”

Because it is impossible to guess a gemstone’s value over the phone, or with emailed digital photos, Khazargems has developed a free online Alexandrite appraisal utility. All that is required to receive an estimated value of your Alexandrite is to enter the parameters of your Alexandrite and you will get an instant approximation of the value of your particular gem. Obviously, the more accurately you answer the questions, the better your appraisal will be. Be assured, your appraisal will be based on the most current values for natural, mined Alexandrite available today.

Currently our Appraisal Utility is Off-Line and being upgraged. Check back soon.

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History of Colored Gemstones

For thousands of years humans have been dazzled and fascinated by colored gemstones. The different colors of gems represented different aspects of the world for our ancestors. Blue sapphires represented the sky and the heavens. Red rubies spoke of fire and love. Green emeralds were representative of birth and life. Golden tourmalines spoke of the sun.

As early as Roman times, different gems represented nobility and many aspects of human emotion such as envy, pride, stubbornness, happiness, temper, and humility. Interestingly, some gemstones had different attributes for men and women. For example: while rubies meant love, strength and fire for men; in women rubies would signify anger, a short-temper and mean-spiritedness!

Gems were attributed with healing powers throughout the middle ages. Different gems were looked upon to strengthen and heal different parts of the body. Gems were worn as amulets and also used to predict the future and protect the wearer.

The zodiac, in ancient China, was represented by animals and gems, while Hindu legend assigned powers to different stones and arranged them by zodiacal signs. The bible mentions gemstones by name in both the old and new testaments. Since Victorian times there has been a language comprised of gemstones wherein different gems mean different emotions such as ‘true love’, ‘constancy’, ‘unending devotion’, etc.

Today, most people know their birthstone, and Natural Alexandrite birthstone of June, being one of the rarest. What most don’t know is that there are lists of gems for most aspects of our lives: anniversaries, days of the week, states of the union, seasons, hours of the day, and many many more.

Today, gems are mainly worn for their beauty and for our personal enjoyment. Gemstones come in many colors, shapes, and sizes; and differ greatly in quality and pricing.


About Natural Alexandrite

Alexandrite was originally discovered in the Ural Mountains of Russia in 1830 and named after the boy Czar, Alexander ll. The old Russian Imperial Colors were red and green and so Alexandrite was only mined for the royalty at that time. The stones found in Russia until 1850 or 1860 (before the mines played out) were considered the best in color and quality in the world until the 1990’s.

In the 1990’s, excellent quality stones were discovered in Sri Lanka, Ceylon, India, Brazil, Burma, Madagascar, Zimbabwe, and Tanzania . The stones from each area have their own characteristics: such as the green color having yellowish tones and the color-change having brownish or raspberry tones from Brazil; and grayish undertones from Ceylon stones.

Recently, excellent quality stones have been found in Sri Lanka, India, and the Tanduru region of Tanzania with all the color and life of an ideal Russian Alexandrite.

 

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Gemstone Cutting

Natural Alexandrite From The Ground To Your Jewelry

Alexandrite mines of India are very dangerous places to visit because the villagers are tribal, very superstitious, and some are “human eaters” ( known to us as cannibals). The villages around the Alexandrite mines have a Tribal Elder, and all mining and selling of natural Alexandrite rough is under his authority.

All payments for Alexandrite rough were made in cash, in U.S. Dollars until 2008. The Elder determines the amount and size of rough that can be bought. There is no bargaining and the sale is “take it or leave it”. With the U.S. Dollar faring poorly around the globe at this time, payment is in Swiss Francs or other, more stable, currency.

Packets of larger and/or graded rough crystals can also be purchased but those are rare and contain fewer total carats and can cost upwards of $50,000 or more per packet. Occasionally, larger pieces of rough may be sold individually for great premiums.

Travel to these villages are dangerous and the conditions are extremely primitive with no, or very little electricity and running water. As soon as the transaction is made the buyer must leave the area as quickly as possible because the local police will be notified of the purchase and they will expect to be paid a bribe- part of which goes back to the ‘whistle blower’.

Rough bought from anyone other than the Tribal Elder, is illegal and considered smuggling. Penalties are very severe with jail being the least that can happen!

The Tribal Elder pays the mineworkers and generally controls the finances of the tribe. There are only three to four times per year that rough is sold by the Tribal Elder. The best time is September through October.

Rough To Finished Gemstones

Once the rough is brought back to the workshop it is sorted piece-by-piece and graded by eye which is very time consuming and difficult. Remember that the initial packet of rough is approximately 2,000 carats and there are thousands and thousands of small pieces contained in small baggies.

About 250-300 carats of rough are considered fine enough to be cut into faceted gems that are considered fine or top quality grade with several additional gradings made according to color, color-change, and clarity. These faceted gems are graded into 1st Grade, 2nd Grade, 3rd Grade, and Commercial Grade. Commercial Grade is formed into beads, and some of the lower grades are sold to other cutters.

Next, each individual piece of the fine quality rough (approximately 250-300 carats) will be examined to determine the best shape for the finished gem. This rough cut will yield approximately 100 carats of the shaped gems with the melee (or scrap) being used to make tiny faceted gems (1 to 1.5mm) and other products.

The 100 carats of shaped gems are then given the 1st Cut with larger facets being placed and cut by eye. This process will yield about 50-55 carats of alexandrite. The 2nd Cut is also done by eye with measurements being taken around the gem for evenness and to place the smaller facets for full coloration and greater brilliance. The 2nd Cut will yield 30-35 carats out of the 50-55 carats.

The final step to producing the beautiful faceted alexandrite that you see on our website is Polishing. The resulting alexandrite gemstone yield is 20-25 carats out of the original 2,000 carats of rough for 1st Grade (VVS) gemstones.

Larger stones are cut by the foreman. The highest quality stones are faceted and finished by the owner and his sons.

To condense this amazing transformation from 2,000 carats of Alexandrite rough to 20-25 carats of finished faceted alexandrite:

  1. Rough: approximately 2,000 carat parcel
  2. Gemstone quality rough in parcel: 250-300 carats
  3. Shaping: yields 100 carats
  4. 1st Cut: yields 50-55 carats
  5. 2nd Cut yields 30-35 carats
  6. Polishing: Final yield 20-22 carats 1st Grade alexandrite

Out of the original 2,000 carats, 2nd and 3rd Grade faceted stones will also be produced. Aproximately 30 carats of 2nd Grade (VS); and 60-70 carats of 3rd Grade (SI) gemstones will be cut.

Most of the rough alexandrite is cut in Oval Facet because its shape will yield a larger carat finished stone. For example, a piece of rough that is cut into a 1.50 carat Oval Facet gemstone will only yield a .90 carat Round (Brilliant) Cut gem.

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Gemstone Mines

 

Gem Mines Of India 1999-2008

After 1999, with the implementation of State Government licensing rules, small areas in India were allowed to be reopened to organized mining with strict governance and conservation measures limiting the amount of minerals and gemstone bearing rock (Pegmatite) taken from the mines. The first of these mines began to produce in the summer of 2000. Since that time, mining has been limited to certain times of the year since rains and monsoons flood the mines for several months and are unsafe to work. The months the mines are closed are usually June, July, and August with production beginning again in September.

With the tsunami in December of 2004, many existing coastal mines were inundated with sea water and walls collapsed, effectively closing the mines. Although some of these mines have been reopened, further mine exploration is taking place further inland although it is fairly limited and the cost of the mining in 2008 has led Indian gem firms to consider investing in foreign mines for the first time. These jewelry merchants are investing in mines in Russia, Africa and even Canada. The Gem and Jewellery Exports Council of India (GJEPC) has initiated talks and is exploring possibilities of investing in existing companies, setting up joint ventures for new mining and even participating in new exploration expeditions.

So far 160 locations have been mapped and identified as possible gem producing areas around the Araku Valley with rich reserves of alexandrite and crysoberyl. Sanctions from the Indian Government, control by Tribal Peoples and the lack of funded organized mining have hindered development of these mines.

Geographically, East 85 degrees Longitudinal bisects the fault from the Ural Mountains in Russia to the area of Andrha Pradesh in India and it is thought that the pegmatite that fought its way to the surface in the Urals over 2,000 million years ago is the same that is now being discovered in the Araku region of India. Certainly the alexandrite being mined in this area of India in one or two mines is of the rich saturation and coloration of the best of the Russian Alexandrite.

The color of Indian Alexandrite tends toward Emerald and bluish-green, with some having grey or blue undertones. 5,000 to 10,000 carats of rough were mined per month for 6 or 7 months in 2004 until the tsunami. The total of carats of rough in 2007 and 2008 have decreased to 2,000 to 7,000 with the larger quantity being mined during July/September/October and the lesser amount being mined in April/May/June.

Andrha Pradesh – Beach Sands – April 2008

There are at least 16 stretches of Beach Sands in this region that have been found to contain good deposits of gem rough, although alexandrite is rare.

Narsipattnamn Gem Mines Of India – 2005-2008

About 100 kilometers from Vishnakahaputnam is Narsipattnanm, where a new alexandrite mine was discovered and opened in 2005. Alexandrite crystal, so far, has been larger than mined elsewhere with satisfactory clarity and color. Within the period of 2006-2008, Alexandrite deposits have produced lighter and less saturated crystal and smaller crystal.

Vishakhapatnam Gem Mines Of India (closed December 2004 and re-opened December 2007)
The area of India known as Andrha Pradesh is particularly rich in natural resources and gems of many types. In 1996 Indian tribal members who worked in the mines in Orissa returned home. They noticed that the soil where they lived was almost identical to the soil surrounding the mines in Orissa and so decided to dig and see what they could find. Initially, what they found was gold!

Whole families started to dig holes and tunnels in the sticky and muddy soil- some as deep as 90 feet in order to mine gold. Along the way they came across rich pegmatite rock with crystals of gems stuck on the rock like cloves on a ham. They discovered that the crystals were wonderful quality alexandrite and emerald as well as other rare gems.

In the early summer of 1996, with rains making the soil even more wet and sticky, an illegal mine with over 60 miners caved in- killing over 16 people and possibly as many as 40 people. The government moved in and closed the area to any mining activity until the land could be mapped and surveyed both by satellite and physical examination of the soil and land.

The tsunami of 2004 closed the Vishakhapatmam mines until the fall of 2007 when further mining and exploration uncovered additional deposits of well saturated alexandrite albeit with a higher percentage of inclusions than in the older mines..

Samunda Gem Mines Of India (Closed 2001)

Alexandrite from the now non-producing Samunda Mine in India are very valuable in today’s market both for collectors and gemologists – especially since the mine only produced for a few years and closed in 2001.

It has been seen that mines where there are wonderful alexandrite tend only to have small pockets of them. That is because these alexandrite are mostly formed in magma pockets where (a) the chemical composition is realigned and changed due to fluctuating heat and (b) then being pushed up under great pressure through wet areas of the earth’s crust where the elements inside are added to and additionally changed. When you think of all the elements and the combinations that can be formed from them, then it is easier to see why the alexandrite finds would be smaller- because the chemical composition and RI are so specific. Conditions for this to happen with the appropriate elements and outside influences are very minute with a color-change gem such as alexandrite.

The essence of the Samunda Alexandrite is its incredible color-change. Some of the stones even change color in fluorescent lighting and it is only in strong daylight and very strong fluorescent lighting that you see the green coloration. The green, by the way, is also very intense- but unlike the Vishakpahatnum Mine, the color looks as though it is being seen through water. In addition, the tone is also darker; therefore the color-change is always more intense. The color-change ranges from vibrant, rich, purple to Amethyst-Violet, to Blood Red and Reddish-Purple.

Alexandrite from the Samunda mines are almost impossible to buy.

Russian Gem Mines

Russia historically has huge quantities of gemstone pegmatite deposits and reserves. With the breakup of the Soviet Union into Russia and Independent States much of these deposits have not been mined due to both economic conditions and the outdated mining techniques from the old Soviet Union.

2008:
Inquiries as to the total amount of Alexandrite being mined at this time in Russia have not been answered as of yet. It is known, however, that Russia has sent mining engineers to Myanmar (Burma) to discuss possible mining alliances. However, with the cyclone in May of 2008 and over 130,000 casualties of the population- mostly by the shoreline, it seems that the discussions are now on hold. Generations of families in the mining industry were casualties as well as the land involved in mining itself.

Areas of Russia that are being mined in 2008 are the Takovaya district in the Urals with alexandrite being mined in schist deposits. There is also a mine in the Takovaya area including Ekaterinburg with a few 23cm alexandrite rough specimens.

2005:
In October 6, 2005 a Russian Mining and Exploration Forum in Moscow, Russia convened. The program called for discussions on developing mineral projects in Russia as well as the technical challenges facing mining and exploration in this region. Of note- a concern being discussed is the assessment and management of environmental issues.

Significant mineral areas in Russia are located in the Urals, the far eastern end of Russia, and eastern Siberia.

One positive aspect of Russian Mining is that DeBeers, a world renown diamond consortium, has stated that it will begin to explore various areas in Russia for new diamond deposits in the fall of 2005. Geologists from both De Beers and Russia have identified over 20 promising areas that are rich in kimberlites (diamond producing rock). A byproduct of this exploration is that it may uncover more of the gem pegmatite bearing rock where alexandrite and other precious stones are found.

1995:
The Siberian Branch of the Russian Academy of Sciences in Russia states that the Takovaja district schists produced great quantities of alexandrite since 1830. In 1995 mining was resumed but due to the low quantity and poor quality of the gems mined there, the mine was closed.

There has been much written about the mining efforts in the Tokovaya region and supposed reports of new finds of alexandrite and other precious gems. To date, little or no significant mining of alexandrite is taking place in Russia.

In October 6, 2005 a Russian Mining and Exploration Forum in Moscow, Russia convened. The program called for discussions on developing mineral projects in Russia as well as the technical challenges facing mining and exploration in this region. Of note- a concern being discussed is the assessment and management of environmental issues.

Brazilian Gem Mines

2008:
The Ministry of Tourism and the Brazilian Institute of Gems and Precious Metals ares promoting gem areas of Brazil for tourists, gemologists and investors to invest in and expand the area’s vast, as yet unmined, deposits.

The areas in Brazil that are being currently explored and mined for chrysoberyl and particularly alexandrite are the Bahia state with grayish 3cm specimens; Espirito Santo in three areas that have uncovered brownish or grayish green specimens.

2005:
The state of Minas Gerais is the site of gem producing mines in Brazil. These mines have produced a multitude of inexpensive gems for over 100 years, but it is only since 1987 that good quality Alexandrite have been discovered at Nova Era (Minas Novas) in enough quantity to export.

As with other mines containing pegmatite, the areas in Brazil are also in very rugged, and often difficult to access, terrain. Mining is under primitive and dangerous conditions, although several of the larger mines are being modernized such as the Hematitia mine which produced fine quality stones for a few years before being played out. Deposits of larger alexandrite are common although the majoritiy of the larger alexandrite is occluded and translucent rather than transparent. Very fine quality larger alexandrite have been mined in miniscule quantity.

2004:
A new pocket of alexandrite was found that has blue-green stones changing to an exciting raspberry-red, although most have been highly occluded. The gem world is waiting to see more of these gems.

The color of the Brazilian Alexandrite tends toward green with brownish tones.

Madagascar, African Gem Mines

2008:
Madagascar: Amboatondrazaka is producing yellow green specimems (as well as Anzakobe and West Ambtomdrasata)

Zimbabwe: Misvingo (Fort Victoria) has produced green alexandrite that is thumbnail size.

Mines in Tanzania and Madagascar have been producing good quality alexandrite for several years and are under the control of the ruling governments although illegal mining is prevalent. The producing pegmatite contains many sized crystals and twinning and chatoyancy are common occurrences.

The mines are in wet regions near rivers and much of the mining consists of picking through the river beds and using shovels and pickaxes to break away rock and dig through to the areas where the pegmatite can be found. Gems and rough in Tanzania go through government auction houses to be sold.

The color of African Alexandrite tends toward gray but Emerald Green has been found in both Africa and Madagascar.

Alexandrite Mining in General
As can be seen by the synopsis of mining for alexandrite in various parts of the world, the bearing pegmatite seems to surface mainly in rugged, wet, rocky terrain, with difficult access. A large majority (over 95%) of the mining is done in primitive and dangerous conditions and most mines are shut down for months at a time due to weather conditions.

These factors and the rarity of gem quality stone make Alexandrite one of the highest sought after, and highest priced, of all gems.

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Gemstone Formation

Natural Alexandrite is formed by nature and mined and cut by man.  Alexandrite are chemical minerals that formed over millions of years deep in the earth. The earth is divided into three segments: crust, mantle, and core. The crust is the top layer –about 5%; the mantle is the second, or middle layer-approximately 28%; and the deepest layer is the core –which is almost entirely composed of molten rock or lava. Gems are formed when molten lava is pushed through to the crust under extremely high pressure in very small quantities. During its travel to the surface through cracks and fissures in the mantle, it mixes with many different minerals in the specific areas it travels giving rise to different gemstones.

The time period between the molten lava leaving the core and pushing its way through the mantle and crust is anywhere from 2,000 million years to 3,000 million years.

Alexandrite and emerald form at a depth of approximately 250km. Diamonds form over 500km and have to push through to the surface without the intermingling of other minerals! Gem bearing rock called Pegmatite cuts through other rocks that act as catalysts and undergo chemical reactions in different stages forming alexandrite, crysoberyl, moonstone, emerald, zircon and different varieties of quartz. The chemicals that act as the catalyst in other rocks are primarily beryllium and aluminum. Alexandrite and emerald are almost always found in the same areas and may even be lustered together.

2008: Mining has produced varying quantities of Alexandrite found in schist.

 

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Need to Know

Purchasing Alexandrite over the internet can be simple. The seller should disclose the Origin of the stone, the Color and Strength of color-changeCut, Size, Weight, Clarity, any Treatment and if the stone is a Natural, not synthetic or lab created stone. Look for size as it relates to carat weight. For example:

Round Alexandrite:

2.0mm = .05 carat +/-
2.5mm = .08 – .09 carat
3.0mm = .15 carat +/-

Oval Alexandrite:

3mm X 2mm= .10 carat +/-
4mm X 3mm= .35 carat +/-
5mm X 4mm= .50 carat +/-

Check out the Clarity. Know that larger stones (over one carat) almost always have small inclusions and stones over 2.5 carats always have inclusions (unless they are over $100,000 and certified). Heirlooms most possibly are synthetic: look out for large carat weight with few, if any inclusions.

Check out color-change. Check to see that the pictures shown are taken in natural light and not filtered or photoshopped. If the pictures are taken in ideal lighting conditions with special light boxes etc, chances are most likely the gem will not appear the same color once it is seen in natural conditions. Also, note that different types of monitors (flat screen, CRT etc.) and different brands of monitors will show colors slightly differently and that settings are set subjectively (such as brightness and contrast). Therefore, carefully read the written description of the color and color-change.

See if there is Certification by an independent lab or a Certificate of Authenticity offered by the seller. Several countries, such as India, have Governmental Regulatory Agencies that will certify the gems.

Know the seller and the seller’s reputation. Call or email the seller to see if questions are answered knowledgebly and promptly. Read testimonials. Check that the seller is a member of professional organizations in the gem and/jewelry industry.

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Natural vs Created or Lab

In viewing natural Alexandrite in daylight it should be a green or bluish-green coloration; the closer to emerald green the better. In warm incandescent light, candlelight or tungsten light the color should change to a reddish-purple, purple, or bluish lavender. The closer the color is to a fine ruby the better the gemstone.

The chemical composition of Alexandrite, for those interested is:

Formula:BeAl2O4
Color: Green/blue daylight and fluorescent light
Luster: Vitreous
Hardness: 8.5 on the Mohs’s scale

Natural alexandrite is a reflective gem and when scratched across a surface (please don’t try this with your gem) it will leave a white streak. Be wary of so-called “natural alexandrite” that are amethyst or pinkish in daylight and change to a purply color in incandescent light. These are NOT natural mined Alexandrite. Also seen are synthetics that are blue or grayish blue in daylight and change to a purply color.

Natural Alexandrite typically have inclusions which can be better seen under magnification. Normal inclusions can include tiny crystals that look like black spots in the interior of the gem, veil like silky threads throughout a the whole or portion of the gem, or even what may look like tiny elongated tubes. Also seen at times in natural Alexandrite are fissures that resemble white or clear lines that look like a crack in the gem.

Besides color differences, any stone that has what resembles air bubbles throughout is a synthetic or created stone. A dusty like appearance within the stone that appears as a dull layer in one level is another indication of synthetic alexandrite. Streaks that travel in the same direction with one end rounded are typical of created alexandrite. Strong color banding that can be easily seen if a gem is placed on its side on a sheet of white paper (look for lighter and darker coloration in layers or bands) is still another indication of created or synthetic alexandrite.

In the last two or three years color change crysoberyl has been sold as Alexandrite. The color may change from green to yellow or bluish to brick brown. Color change crysoberyl is NOT Alexandrite. The parameters of color within Natural Alexandrite are limited to the colors listed earlier in this article.

Lab grown Alexandrite is also being sold as Natural Alexandrite or even Natural Russian Alexandrite when the lab is located in the USSR. Although a competent lab or gemologist can tell whether the stone is lab grown or natural mined, the differences are too minute for the consumer, so one has to be very careful.

The bottom line is: know the seller’s reputation. Khazargems has a wide variety of Natural Alexandrite mined from the earth- no lab, synthetic or color change crysoberyls are ever sold by us.

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Viewing Color Change

When you view the color and color change of an Alexandrite, it should conform to these standards.

  • It should be green in sunlight and fluorescent light.
  • It should be purple, red, or reddish-Purple in soft incandescent light. A low-lit room is the best place to see the color change. Light from a candle will also show the purple color change. Very, very infrequently an alexandrite will exhibit a change to a more reddish color- reddish-Violet, Violet-red etc. These gems command a great premium in price.
  • Mixed light will produce either a grayer color as the green and purple mix or flashes of the green, purple, and sometimes red or yellow. Strong color-change stones will usually show the red/purple color in mixed lighting
  • Rotate the stone to get the color from all facets and to look for ‘flash’ (blazes of color that show in the body of the stone). Ruby-red and hot-Pink flash and sparkle is the most desirable and most rare.
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How To Buy An Alexandrite

 

When it comes to a color-change Gemstone there is more to learn than Color-Cut-Clarity-Carats, or the 4-C’s as they are commonly known. Gemstones that change color depending on the light they are seen in (also called Phenomenal Gems), are judged by different standards than other gems.

Learn about the history and beauty of these most desirable of gems and how the experts grade them. Learn how to buy Alexandrite on the Net or at your neigborhood jewelry store.


Color  Changing Gems And Chemical Composition Of Alexandrite

In the world of gemstones, there are those special and rare few gems that exhibit a mysterious change of color dependent on the light they are shown in. These gems are called color-change or Phenomenal gems. Although color-change tanzanites, sapphires, quartz, spinels, crysoberyls, garnets, tourmalines, and fluorite (to name a few) occasionally can be found there is only one known gem that always has a color change: Alexandrite.

Alexandrite is the only gem that has a standard and that standard states the gem must change from green in daylight to purple or reddish purple (the more red the better) in incandescent light or candlelight.

Color-change in other gems run a gamut of colors: from purple to pink in Amethyst, purple to blue or even green in Tanzanite, green to red or yellow in Garnet, green to yellow or orange or blue in Tourmaline; the changes and colors run the spectrum of the rainbow. Alexandrite is the only gem that has a standard and states the gem must change from green in daylight to rich ruby red or violet/purple in incandescent light or candlelight.

Chemical Composition Of Alexandrite And Color-Change Chrysoberyl

Alexandrite is a specific type of color change chrysoberyl. The chemical composition of chrysoberyl and color change chrysoberyl is BeAl2O4. Chrysoberyl is in the Class called Oxides. The crystal system is orthombic and the crystals themself are commonly twinned which results in a triangular shaped crystal or a crystal within a crystal. While I could list all the known properties of chrysobery the most important issue is that Natural Alexandrite, which is chrysoberyl has at least one important difference between itself, normal chrysoberyl and color change crysoberyl. In Natural Alexandrite there is a replacement of some of the alumina in the molecular structure by chromic oxide causing Natural Alexandrite’s specific coloration. Color change chrysoberyl does NOT have this replacement.


 

Color

The color of a GIA Type 2 gemstone is of paramount importance. The more pure the color (hue), the less a difference cut, clarity and carat weight have on the beauty and value of the stone.

Color is subjective; however in colored gemstones there is a standard that is considered the appropriate and most beautiful color for that gem. In color-change gemstones, of which Alexandrite is the only one in nature in which 100% of the stones change color; the Standard states the gem must show as bluish green or Emerald green in daylight or fluorescent light and red or purple in incandescent or candlelight.

The color and strength (percentage) of color-change is another important factor. Most gemologists refer to the strength of the color-change by percentage (with 100% being ideal and stones below 30% not considered) or terminology (weak, moderate, strong). Alexandrite with 100% color-change will show completed color-change on every axis of the gem– all the facets will change color. Looking down through the table of the gem, if half the facets change color the gem is classified as a 50% change, if three-quarters change color it is a 75% color-change etc.

Color is described in gems through: Hue– the exact color in the spectrum (red, orange, yellow, green, blue, indigo, violet); Intensity or Saturation– the brightness or dullness of the color; Tone– how light or dark the stone is (how much black or white is present); Distribution– the evenness of color throughout the stone (Zoning). When reading a description of the color of a gem if there are mixed hues, the predominant hue is Capitalized and the lesser hue is shown in lower case. For example: bluish-Green; Green is the predominant color and blue is the lesser (underlying) color.

Note that in the last few years, unknowing or unscrupulous sellers are marketing color-change chrysoberyl as Alexandrite. Although Alexandrite is a specific form of chrysoberyl with both having a chemical composition of BeAl2O4, it is the very small replacement of alumina in chrysoberyl by chromic oxide that causes the alexandrite’s characteristic and standard coloration.


 

Carat

Gems have been standardized in weight since 1913. All gems (except pearls and coral) are weighed in Carats. One carat equals 200 milligrams (1/5 of a gram). The Carat is a unit of weight- not size! A rule of thumb: multiply the gram weight of a stone by 5 and you will have the carat weight (example: 0.06 grams=0.30 carats).

Gems have different densities. If you take a one carat ruby and compare it to a one carat emerald there will be a difference in size because ruby is denser than emerald. Therefore, the ruby will be smaller than the emerald even though both WEIGH the same and therefore have the same carat weight.

For each type of gemstone- sizes (in millimeters) will yield specific weights (carats). To reference Natural Alexandrite, for example: round stones of determined mm (millimeters) will always fall into a very small range of carat weights such as a 2mm= .05 carats, 2.5mm= .08 or .09 carats. Any large deviation from the referenced sizes would mean that the stone was either cut shallow (example: 2.5mm= 0.4 carats) or deep (example: 2.5mm= .14 carats). If a stone is cut too shallow the color will be washed out or too light, and if a stone is cut too deep the stone will appear too dark).

Mining of gem quality alexandrite is extremely rare in sizes over .25 carat. Stones that are less than .50 carats can sell for thousands of dollars. Stones over one carat usually cost in the tens of thousands of dollars for fine quality, while stones over three carats, that are naturally mined, can cost close to $100,000.


 

Clarity

Clarity can be described as the degree of absence of inclusions (foreign particles, bubbles, fissures etc. in a stone). Alexandrite is a Type 2 GIA gemstone, which means that the norm is for a stone to have minor inclusion (silk, negative crystals, fissures etc). A clean faceted Alexandrite up to a carat in size is rare and above one carat is extremely rare. Therefore, a VVS Alexandrite (which is the highest classification) is described as: Very Very Slightly Included – Minor inclusions.


 

Cut

Alexandrite is found in several shapes with oval facet being the most common (and having the least waste material after cutting). Round has the most waste after cutting which renders the stones a premium in price. More alexandrites are now being cut in other shapes such as, pear, cushion, emerald, fan, baguette and fancy cuts.

Most alexandrite are native cut- that is, they are cut and faceted in the country in which they are mined by craftsmen that have been trained from father to son over many generations. The cutting and faceting is all done by hand and not by machine.


Alexandrite Prices

Natural Alexandrite Prices of all origins as of May 1, 2008 as reported by the International Gem Society are as follows:

Top Red/Green (90%-100% Color Change)
0-0.5 carat
$2,500 to $6,000/ct+
0.5-1 carat
$5,000 to $15,000/ct+
1 carat and up
up to $1,000,000/ct
Medium Red/Green (70%-89% Color Change)
0-0.5 carat
$1,500 to $6,000/ct
0.5-1 carat
$1,500 to $9,000/ct
1 carat and up
up to $60,000/ct
Slight Red/Green (30%-69% Color Change)
0.5-1 carat
$100 to $2,500/ct
1 carat and up
up to $6,000/ct
Cabochons – Strong Red/Green
0.3-1.5 carat
$500 to $2,500/ct
1.5 carat and up
up to $30,000/ct
Cat’s Eye – Strong Red/Green
All Sizes
$1,500 to $5,000/ct

Top Red/Green does not mean that the alexexandrite changes from Ruby Red to Green. It is well known that 99.99% of all alexandrite do not exhibit such a color change. Rather, the well known coloration is Purple/Green. The more Red in the gem in warm incandescent lighting the more valuable the stone.

Other Coloration in Alexandrite: Any color change that is not Green/Purple. The daylight coloration must be a shade of green, and the incandescent coloration a varient of red/purple such as rust, brownish, orangey.

Retail price is determined not only by the value of the gemstone or jewelry itself but also by market strength, geographical location, and other factors including, but not limited to; cut, proportioning, color-change, finish.


Imitations

True synthetic Alexandrite have been lab grown in Russia from Corundum for the past ten to twelve years. These stones are being marketed in some quarters as Russian Alexandrite, Natural Alexandrite, and even Natural Russian Alexandrite. As early as 1907 or 1908 synthetic Alexandrite were created from synthetic color-change sapphires colored by vanadium. Since these stones have been in circulation for several generations it is entirely possible for families to think that an heirloom Alexandrite is a true natural, mined, Alexandrite. Visitors to foreign countries buy heirloom Alexandrite thinking it is natural when, in fact, many times it is a cheap synthetic sapphire worth only a few dollars.

Hopefully this article has answered a few of your questions and you now have a better undestanding of what is important and how to buy Alexandrite.

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Color And Gemstones

Color is in the eye of the beholder. People see color differently depending on many factors including eye color, geographic location, atmospheric conditions, time of day and altitude. We will take the most common differences and explain how they affect the way we see color in gemstones.

Purkinje Shift

The Purkinje Shift is the name of the phenomena that states the human eye has the ability to perceive color according to the amount of light that hits it.

Dimmer light fires more of the blue wave length which means that blues will seem more vivid, while more intense light will fire more of the red wave lengths which makes red more vivid. So: blue sapphires are better seen in dimmer light and red rubies in brighter light. Alexandrite, having a Refractive Index (RI) between that of Emerald and Ruby, shows its green coloration best in bright, indirect light and the Red/Purple coloration best under dim incandescent light with warmer tones.

But wait- a second factor that affects how we see color is that different eye coloration (blue, brown, hazel etc) significantly sees color in differing spectral hues. Blue eyes can differentiate over 30% more hues than dark color eyes. Therefore, when a seller in Asia with dark eyes picks out a gem and describes its hue, a buyer in a European country who might have lighter or blue eyes will see the same gem in a different hue. Add in the retail buyer and the difference in perception of color can be even further from the original described hue.

A third factor in seeing coloration in gemstones is atmospheric condition. Hot, high, dry and sunny locations (such as Jaipur, India) shows intense coloration; and cool, low, humid and cloudy locations (such as the coast of Thailand) show coloration as darker and drabber.

Most agents send photographs of their gems to their purchaser. And most sellers take pictures and list the pictures on their websites or in eBay or in a paper advertisement. Another factor to color is the fact is that a camera ‘sees’ light and color as static and that computer monitors have different settings and basic color differences. This does not allow the color of a gem such as alexandrite (that has three axis and shows color a bit differently according to the axis) to be seen as ‘true’. Many color-change gems also will show part of the color change in a photograph if the photographer is not careful to filter out extraneous light sources.

So what can you, as a buyer do? If possible, look at the gem in person, rather than in a picture. If that is not possible, know your seller and check out the written description of the color of the gem and see how much it differs from the photo. You can email the seller and ask for a more detailed description of the color. It is important to remember that personal preference is primary if the gem is to be worn and enjoyed. In natural alexandrite, the standard for color is an intense Emerald Green in daylight and a change to rich Purple in incandescent or candle light- the more red tones in it the better.

At the present time, bluish-Green seems to be the most popular daylight color with a change to rich Purple the most popular incandescent coloration.

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