"Benitoite" - the Blue Diamond of California !

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Sometimes called the " blue diamond", it was first discovered near the headwaters of the San Benito River, in San Benito County, California in 1906, from which it derived its name. It was at first thought to be a varirty of Sapphire, because of it's blue color. The gem is extremely rare and ranges in color from a light transparent blue to dark, vivid sapphire blue, and occasionally it is found in a violet shade. Benitoite is a somewhat obscure, but it is a wonderful gemstone. Benitoite was designated as the Official State Gemstone of California in 1985.

Benitoite is associated with a few rare minerals such as black-red Neptunite, snow white Natrolite and brown-yellow Joaquinite . The only source of this rare combination occurs at San Benito, California. A rare cluster of blue Benitoite and black Neptunite on top of a crust of white Natrolite is a treat for collectors. Gems much over one carat are uncommon. The sapphire-blue or colorless crystals are small. Gem quality specimens larger than two carats are rare. Faceted stones are usually under 1 carat, the largest documented stone is 7.8 carats and resides at the Smithsonian. Benitoites sell for over $1000 per carat and the price has been raising rapidly as the deposit has been largely worked out and available gems sold.

In 2000, Brian Lees of Colorado purchased the site from the long time owners. He brought in a mining crew and worked the mine for five winters. The current owner is now Dave Schreiner who bought the mine from Lees in 2005. Dave's vision was to open up the mine to collectors, since it is probably the most famous gem location in the world, and is on everybody's list of "places to collect." So now thanks to Dave Schreiner, gemstone and mineral collectors alike have that rare opportunity to come and try and find this unique and rare genstone.

California is a virtual cornucopia of gems, with the best known being Tourmaline, Kunzite, Serpentine and Topaz, all available to the public at open mines where you can buy buckets of dirt to dig through. In recent years, top-notch finds have helped restore the region’s splendor.

Serpentine, a green Jade looking material, is considered the State rock and of course Native Gold, a picture of which is shown at the right, is the Official State mineral. Of all the states where gold is found, only Alaska also considers Native Gold to be its State mineral.

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BLUE AMBER - a Total Surprise !

Typical rough Amber pieces from the Baltic

Amber, that strange material that hardened from several species of tree resins from several hundred million years ago. The best known Amber is from the Baltic Region, but it also comes from Africa, the Arabian Peninsula, North and South America and some Islands in the Caribbean. But do not confuse Amber with Copal, Copal is the new kid on the block being only a few million years old and in most cases much softer, coming from Columbia and a few Caribbean Islands.

Piece of Dominican Blue Amber as seen in the rough

Amber is supposed to be amber color, right? Not exactly. There is the original colors of Amber, yellow, orange, honey, cognac or similar. A new delight among jewelry designers is Butterscotch Amber, found in the Baltic as well as the Middle East. But there also is cream, cherry, red, green and even blue, which is by far the rarest of all the Ambers. Up to this day many people do not believe in the existence of "BLUE" amber. Must be something in the air or in the ground, since two of the more highly prised gemstones that come from the Dominican Republic are both "BLUE" - Blue Amber and Larimar.

Chunk of Dominican Amber with Reds-Cognac-Yellow coloring.

Is Blue Amber Truly Blue? No. It is not. And yet, it is. Confused? Blue Amber is a result of fluorescence and no solid color exists. Ultra-violet or violet light is re-emitted as blue or green light, attributed to the presence of poly-nuclear aromatic molecules. Therefore, Blue amber is blue, but not the way you might think.

When sunlight strikes the Blue Amber on a white surface the light particles pass right through and are refracted by the white surface. Result: the Blue amber looks almost like any other Amber, only with a light blue hue. But when the light particles can't pass through and refract back, the hydrocarbons in the Blue Amber turn the sun's ultraviolet light into blue light particles. The result: the famous blue glow of Blue Amber. This effect is only possible with Dominican Blue Amber pieces graded within the Blue Amber category. Any other Amber (like Baltic and others) will not display this blue phenomenon at all. And, on top of that other Dominican Amber will show this blue efraction only in concentrated UV light, and not in natural light. Light passed through the Blue Amber from a flashlight, will also result in the normal looking cognac amber color.

Example of same piece of Blue Amber with front lighting, then looking as same piece lighted from the reverse

Thanks to The Amber Ranch for the pieces of and the info on Dominican Blue Amber

BLACK CORAL - An Endangered Species !

Black corals (Antipatharia) are a group of deep water, tree-like corals related to sea anemones. Although the most famous are found near Hawaii, they are also found in rare dark shallow water areas such as New Zealand's Milford Sound where they can be viewed from an underwater observatory. They normally occur in the tropics and some have ben found in the Caribbean. Though black coral's living tissue is brilliantly colored, it takes its name from the distinctive black or dark brown color of its skeleton. Also unique to black coral are the tiny spines that cover the surface of the skeleton, the origin of the nickname little thorn coral. In the Hawaiian language, black coral is called ‘ēkaha kū moana. Black coral is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES).

The Black Coral which grows in Hawaii's offshore waters was adopted as Hawaii's official state gemstone on April 22, 1987. Since its discovery by early Hawaiian divers, harvesting of the spectacular corals has led to the establishment of a thriving Black Coral jewelry industry and enhanced visitor and resident appreciation of Hawaii's ocean resources.

Hawaii's state gem was promoted by scuba divers, perhaps supported by the local jewelry trade. Surprisingly, the Department of Land and Natural Resources testified in favor of its adoption. Coral’s richly colored branches are living gems formed deep beneath the ocean. These precious corals polish to a gorgeous luster and have been used as gemstones dating as far back as 25,000 years—longer than pearls. Each coral gemstone color has its own distinct quality. Black Coral is exotic and dramatic and has long been considered to guard against misfortune. Pink Coral is delicate and is said to bring good health. Red Coral is best described as rich and romantic. And Gold Coral with its mysterious inner light, is the rarest of all corals.

The first new Black Coral bed found in centuries outside of Caribbean waters was discovered in the waters off Lahaina, Maui in 1958. Today, Hawaiian Black Coral -- the world's finest -- is carefully collected by hand by divers at depths that exceed 200 feet. To ensure the future of Hawaiian Black Coral, divers must strictly adhere to state regulations that prohibit the harvesting of immature colonies. Harvesting of Black Coral is prohibited in most locations in the world.

Black Coral is rare and, when polished, it shines with such luster you can almost see your own reflection in it. Its stunning contrast against yellow gold makes it a wonderful gift as well as a beautiful keepsake to treasure forever. Black Coral gives one a perfect reminder of a trip to the Islands.

As with many gemstones today, be careful that what is being bought is genuine Black Coral and not faux, plastics or other imitations that abound, especially in the Caribbean.

Coral Fossils for Jewelry !

Natural Coral Fossil cut as a Pendant

Corals are simple animals that secrete skeletons made of calcium carbonate. They are close relatives of sea anemones and jellyfish and are the main reef builders in modern oceans. Corals can be either colonial or solitary.

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As fossils, corals are found worldwide in sedimentary rocks. Based on these fossils, we know that the corals began their long evolutionary history in the Middle Cambrian period, over 510 million years ago. In Kansas, they were deposited from about 315 to 250 million years ago. Nice coral fossils are found in Pennsylvanian and Permian rock formations. Although corals are the main reef builders in modern oceans, not all corals build reefs. In addition to the corals, which are called framework organisms, other organisms contribute to the formation of reefs. For example, modern reefs are inhabited by binding organisms (such as encrusting algae) and filler organisms (such as snails, bivalves, and sponges), whose skeletons fill in the spaces in the reef after death.

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Two groups of corals were important inhabitants of the Pennsylvanian and Permian seas--tabulate and rugose corals. Tabulate corals were exclusively colonial and produced calcium carbonate skeletons in a variety of shapes: moundlike, sheetlike, chainlike, or branching. Tabulate corals get their name from horizontal internal partitions known as tabulae. Some tabulate corals were probably reef builders..
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Pink Coral Fossil and Indonesian Coral Fossil are among the most commonly found Coral Fossils used in todays jewelry.

Coral fossil material displays the unusual internal structure of the original coral. Coral fossil cuts and polishes like Agate, but in most cases are a bit softer.

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Red Eye Coral and Black Eye Coral are two of the more unusual types of Coral Fossil found in present day markets. Both come from sea floors around South East Asia.

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Sponge Coral ! That's its trade name. It is known to marine biologists as melithaea ochrace. A sponge coral really has nothing to do with sponges. It just looks like a sponge. Found mainly in the South China Sea, from Taiwan down to Indonesia, the sponge coral has a distinct fan-shaped appearance underwater. Until recently, sponge coral was not used for jewelry as they weren't considered jewelry-quality coral because they contained too many holes. However with the "farming" of man-enhanced Sponge Coral, we now have a renewable source and thus the harvesting and use of other natural corals is becoming more and more controlled, even to the extent that importation of coral is illegal into many countries without special government issued licenses, however Sponge Coral does not fall under these regulations. The majority of Sponge Coral used in jewelry has to date been shades of reds and oranges.

A very rare pure White Coral Fossil.

The coral can be cut and placed into very fine jewelry, such as this Black Coral ring. However, coral is best used in earrings and pendants, as its softness can allow it to be easily damaged in jewelry such as rings, unless properly protected.

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And of course in todays market place we have all kinds of fakes and man made gemstones. Although natural, colored coral fossil stones are normally found to have been helped a bit with some colorations from man.

Michigan's 'Green Turtle Stone' - "CHLORASTROLITE" !

YES, there is a stone known as the "Green Turtle Stone" It was not made up by some kids to cause a sensation.

In 1972, Chlorastrolite became the official State Gemstone for Michigan. Chlorastrolite is a beautiful green mineral with a chatlyant "turtle-back" pattern. Don't feel too bad if you are unfamiliar with the name. First of all, it is quite uncommon. Gem varieties are only found in Michigan. Secondly, there has been some confusion over the correct name as well as its true identity. It has been considered to be a Zoisite, a variety of Prehnite and a variety of Thomsonite. It has been called lotrite, kearsargeite, zonochlorite, lintonite, pumpellyite, chlorastrolite and greenstone. After much research, the IMA has ruled that the gem we are talking about is to be called "Chlorastrolite," - Michigan collectors still call it by the common name, "greenstone" or "Turtle Stone".

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Chlorastrolite occurs in the basalt layer deep under the Keweenaw Peninsula. When Isle Royale was formed off-shore from Keweenaw by an upheaval of the bedrock under Lake Superior, some of this material was brought to the surface. This tilting of the bedrock exposed the greenstone-bearing basalt. Wave action erodes the greenstones free and they may be found as beach gravel on the Isle. For many years this was thought to be the only source of the gem. When first offered in jewelry by the NewYork fashion stores in the 1890s, they were referred to as "Isle Royale Greenstones." To this day, many persons fail to realize that much of the Chlorastrolite occurred under the Keweenaw Peninsula and was discarded on mine dumps by the copper miners when they tunneled to the copper. The mines are not operating now and new material is not being brought to the surface, but the greenstones are usually overlooked by the rockhounds searching for copper. You can find gem-quality Chlorastrolite at the mine dumps if you look carefully. Greenstones have been found at most of the mines at Keweenaw; however, some mines produce better greenstones than others. The Central Mine, located just off US 41 north of Calumet, has been the most recent source of some of the largest greenstones.

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So as not to raise to much confusion or start an arguement over what is Michigan's selection, one needs to also know that Michigan's State Stone, which is much better known, especially to Lapidarist, is 'The Petoskey Stone'. Petoskey Stones are masses of fossil colony coral, Hexagonaria Percarinata. They occur abundantly in Devonian reef limestones of the Traverse Group in the northern part of the Southern Peninsula of Michigan. The Devonian Period was about 350 million years ago. Coral groups weathered out of the limestone were widely scattered by Pleistocene glacial action. They are readily found on beaches and in gravel deposits as pebbles and cobbles rounded by erosion. Petoskey is the English adaptation of either "Be-dos-e-gay" or "Petosegay," an Ottawa Indian word and variant meaning "sun rays of the dawn."

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INTERESTING GEMSTONE ROUGH

It is always interesting to find very showy gemstones, but some just seem to stand out from the rest. The following are some examples of not new stones, but interesting ones that are not seen very often and when found are grabbed quickly by those who know what they are.

KOROIT Boulder and Matrix Opal material from Australia.

What is so interesting about the KOROIT material is the varied colors.

Then there is the stone that when someone claims to be a gemologist, you ask them about - MAW SIT SIT which comes from the northern area of Myanmar (Burma). Maw Sit Sit is a unique arggregate metamorphic rock.

Another Australian find from the back-country is the ANDAMOOKA Opal material.

Then close to home we have CHALCOPYRITE, a copper-iron-sulfite material better known as Peacock Stone to those in Arizona.

And then a fairly new stone on the market, SONORA SUNRISE, a combination of Chrysacolla-Cuprite-Malachite that was found in the region around Sonora, Mexico.

And the new kid on the block in terms of new finds. Wello opals were discovered in 2007 in Wello, Ethiopia. Since then, Wello opals have been captivating the gem world.

PYRITE - The "Fools Gold" Stone

Lets start by how you may see Pyrite when looking for it. First it could be a 'cube' attached to a host rock, or a bunch of small 'crystals' in amoung other crystals such as Quartz, or maybe the real fooler, a Golden Pyrite "clump'. These are not the only way Pyrite appears however, as can be seen in several of the following pictures.

There are several shiny brassy yellow minerals, but pyrite is by far the most common and the most often mistaken for gold. Whether it is the golden look or something else, pyrite is a favorite among rock collectors. It can have a beautiful luster and interesting crystals. It is so common in the earth's crust that it is found in almost every possible environment, hence it has a vast number of forms and varieties. During their search for forture, many infamous shouts ocurred amid the Old West propsectors "There's Gold in that Riverbed !" only to be disappointed in finding Pyrite or as the golden rock quickly became known as "fools gold". Many a gold seaker was fooled by this shiny yellow mineral that looks so similar to gold.

Pyrite is a polymorph of Marcasite, which means that it has the same chemistry, FeS2, as Marcasite; but a different structure and therefore different symmetry and crystal shapes. Pyrite is difficult to distinguish from marcasite when a lack of clear indicators exists, as can be seen by the following picture of a piece of Marcasite.

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Almost any rock that looks a little rusty will mostly likely contain some pyrite. Pyrite is cubic crystals composed of iron sulfide; spherical and bulbous pyrites also exist; it is found in large quantities, mainly in coal mines and near clay workings. It comes in a vast number of forms and varieties, but the most common crystal shapes are cubic and octahedral.
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One sought-after form is flattened nodules found in chalk, siltstone and shale called “pyrite suns’ or ‘pyrite dollars’. These nodules are usually made from thin pyrite crystals radiating from the center.

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Enourmous amounts of small Pyrite crystal clusters come from Oruro and Colavi, Bolivia. In Navajun (Logroño), Spain, large cubic crystals, are abundant. They are frequently embedded in a light brown matrix, and are occasionally twinned.

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Perfect crystals occur in Rio Marina on the island of Elba, Italy. In the U.S., there are also many fine localities. In Park City, Bingham Co., Utah, very large, well shaped Pyritohedrons and Pyrite Cubes have been found, as well as in the American Mine in the Bingham Canyon, Salt Lake Co., Utah. Large, intergrown cubes, many times partially octahedral, occur in abundance at Leadville, Lake Co., Colorado. Pyrite "Dollars" are mostly found in Sparta, Randolph Co., Illinois. The French Creek Mine in Chester Co., Pennsylvania is famous for the octahedral crystals that occur there, although most are distorted. Many interesting nodules were recently discovered in Alden, Monroe Co., New York.

The use of Pyrite in decorations is also quite common. How many times have you visited a mine to see mining scenes in Pyrite avaiable on the sales counters.

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And more recently, Pyrite has been faceted so that it can be made into jewelry such as rings, pendants or earrings.

Pearls - Looking at the inside !

The first thing to point out is that there are several types of oysters and mollusks that are used to produce pearls, both salt-water and freshwater. I am not going to go into the different kinds of pearls in this discussion, just what the inside of all of them basically look like. Borrowing some photographs from the International School of Gemology (ISG) where gemology is taught based on actual specimens of gemstones: natural, synthetic and organic, rather than from pictures in books, we will take a look at the inside of a pearl For this discussion, the internal differences between a salt water Akoya cultured pearls and a Chinese freshwater cultured pearl will be looked at. At the end, a new surprising find will really make one wonder.

Above is seen a 5mm pearl purchased as an Akoya cultured pearl. Notice that it is uniformly round from the seed all the way out to the outer nacre layer, which is the thin line you see at the very edge of the pearl. What was quite remarkable about this pearl is that the center of the pearl is a hollow plastic looking bead, not the Mississippi mussel shell bead that was expected. You can see the circular structure of the Akoya cultured pearl with the bead and resulting layers being rather uniform from center to outer nacre layer.

Now above you see a freshwater cultured pearl from China . These are called non-nucleated pearls since they are started with a ball of tissue rather than a pre-formed bead. The picture is quite graphic to show that the center of this pearl is a somewhat organic looking mass of old tissue rather than a well formed starter bead as seen in the Akoya pearl. These pearls have been back lit to allow one to see the difference in formations, which is rather pronounced and graphically demonstrates the basic difference between the salt water Akoya and the freshwater pearl.

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A question was asked that perhaps since the freshwater pearl was started by what is basically a ball of tissue, that should there not be some kind of hollow place in the center of a freshwater pearl as the tissue degenerates during the growth process? And sure enough, when the viewing angle is changed on the freshwater pearls, one can see hollow places in the pearl as seen in the pictures below of a half drilled 5mm freshwater pearl.

Thus these pictures show what would be seen if you dissect one of those expensive little jewels you have on that string of pearls you got as a gift.

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Now for the surprise. How about opening up one of those very expensive Tahitian South Sea Pearls which are known for their excellent quality and thick nacre layer. But what’s really inside one of those Tahitian pearls? Well, one was cut open and to the surprise of everyone, what was found is almost beyond comprehension !

The center is a plastic bead. Apparently someone has found out how to use plastic instead of natural material to get the Pearl to form.

And taking it one step further, perhaps a reused piece of plastic for the starter bead. Why the multiple holes in the starter bead? Was the pearl farmer recycling plastic? Why place a used, multi-drilled plastic starter bead inside an oyster to make what could turn out to be a very expensive South Sea Tahitian Pearl in the first place?

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But then again, it is this type of perplexing problems that is what makes gemology so much fun and of interesting experiences. A lifetime of learning and sharing the wonders of the earth.

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Again thanks to the ISG for the use of pictures and information.

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Metal Clay in Jewelry Making !

For many jewelry makers who have dreamed of working with metal but have had nightmares about using the torch, Metal Clay, also called Precious Metal Clay (PMC) and Art Clay, may be their dream come true. However, keep in mind that while you don't need to use a torch to necessarily solder metals together, it can be helpful to know a little about metal work in order to clean and finish metal clay pieces.

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Metal clay is a clay-like medium used to make jewelry, beads and small sculpture. It consists of very small particles of precious metals (such as Silver, Gold or Platinum) mixed with an organic binder and water. Metal clay can be shaped just like any soft clay, by hand or using moulds. After drying, it can be fired in a variety of ways including in a kiln, with a handheld gas torch, or on a gas stove. The binder burns away, leaving the pure, sintered metal. Shrinkage of between 8% and 30% occurs (depending on the product used), but this is exploited by artisans to produce very fine detail.

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Silver metal clay results in objects containing .999 pure silver - aka fine silver, which is ideal for enameling. Although gold metal clay is much more expensive to use, the color and richness is phenomenal. It can be used to make stunning solid gold objects or used sparingly to make beautiful accents on silver pieces. Lump metal clay is sold in sealed packets to keep it moist and workable. The silver versions are also available as a softer paste in a pre-filled syringe which can be used to produce extruded forms, in small jars of slip and as paper-like sheets, from which most of the moisture has been removed.

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There are two popular brands of this material, Precious Metal Clay (PMC) and Art Clay Silver (ACS).

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Precious Metal Clay or PMC was developed in the early 1990s in Japan by metallurgist Dr. Morikawa. The material consists of microscopic particles of pure silver or fine gold powder and a water-soluble, non-toxic, organic binder which burns off during firing. Success was first achieved with gold, and later duplicated with silver. The original formula of PMC, now called "Standard", must be fired in a kiln at 900 °C (1,650 °F) and has a shrinkage rate of 30%. Mitsubishi Materials Corp later developed two additional versions of silver called "PMC+" which can be fired as low as 810 °C (1,490 °F) for 30 minutes, and "PMC3", which can be fired as low as 599 °C (1,110 °F) for 45 minutes. Both PMC+ and PMC3 have a shrinkage rate of 12-15% and may also be fired with a handheld torch for 4-7 minutes. A 22k gold gilding material called "Aura 22", and lump 22k yellow gold clay (an alloy of fine silver and gold) are also available. PMC also manufactures an 18k gold clay and a platinum clay, but these latter two are only marketed in Japan.

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Art Clay Silver or ACS was developed by AIDA Chemical Industries, another Japanese company. Art Clay followed PMC Standard with their Art Clay Original clay (more like PMC+ than PMC Standard), which allows the user to fire with a handheld torch or on a gas hob. Due to subtle differences in the binder and suggested firing times, this clay shrinks less than the PMC versions, approximately 8-10%. Further developments introduced the Art Clay Slow Dry, a clay with a longer working time. Art Clay 650 and Art Clay 650 Slow Dry soon followed - both clays that can be fired as low as 650 °C (1,202 °F), allowing the user to combine the clay with glass and sterling silver which are affected negatively by the higher temperatures needed to fire the first generation clays. AIDA also manufacturers Oil Paste, a product only used on fired metal clay or milled fine silver, and Overlay Paste, which is designed for drawing designs on glass and porcelain. In 2006 AIDA also introduced the Art Clay Gold Paste, a more economical way to work with gold. The paste is painted onto the fired silver clay, then refired in a kiln, or with a torch or gas stove. When fired it bonds with the silver, giving a 22ct gold accent. The same year also saw Art Clay Slow Tarnish introduced, a clay which tarnishes less rapidly than the other metal clays.

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A do-it-yourself version called Silver Smith's Metal Clay Powder is available in a dry powder form to which the user adds water to obtain any desired consistency.

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This book is a great guide for getting a start in Metal Clay Jewelry.

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FACETED GEMSTONES - One choice for a list of the Rarest !

Not without some controversy and easily finding several different listing on various sites on the internet, lets look at 10 Faceted Gemstones that can stir up debate about them being the 10 rarest. But whatever list one uses, they all have one thing in common - they are all very very expensive.

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PAINITE has been described as the rarest gem mineral. As of early 2005 there were eighteen known specimens, all numbered and accounted for. Specimen No. 5 has been faceted into an oval and weighs 2.54 carats. Painite is pink to red to brown in color, very strongly pleochroic (showing different hues from different angles) and it fluoresces a lovely green under short wave UV. It comes from Mogok and Kachin State in Myanmar.

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SERENDIBITE, not to be confused with serandite, comes from Sri Lanka. It boasts an unusually complex formula consisting of calcium, magnesium, aluminum, silicon, boron and oxygen. So far there exist three faceted specimens. The name comes from the old Arabic term for Sri Lanka, Serendib, as referenced in The Sixth Voyage of Sinbad.

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.POUDRETTEITE, another of the purple gemstones from Magok, Myanmar, was discovered in 2000. By December 2004 nine gem-quality pieces had been found , including a pale pink. At a Mohs hardness of 5, Poudretteite is the softest stone on this list — too scratchable for a ring but suitable for earrings, a pin or a pendant if care is exercised. Previously this substance had been known as a rare mineral of tiny colorless crystals, discovered in 1987 and named after the Poudrette family that operated the source quarry at Mont Saint-Hilaire, Quebec.

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GRANDIDIERITE is a bluish green mineral found primarily in Madagascar. The first and so far only clean faceted specimen, from Sri Lanka, was originally mistaken for a serendibite. Grandidierite is trichroic, transmitting blue, green and white light. The mineral is named after French explorer and natural historian Alfred Grandidier, who among other things unearthed bones from the extinct half-ton elephant bird in Ambolisatra, Madagascar.

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JEREMEJEVITE is a colorless, sky blue or pale yellow stone, the highest quality of which comes from Namibia. In nature it occurs in small obelisk-shaped crystals and has in the past been mistaken for aquamarine. It was named after Russian mineralogist Pavel Jeremejev who discovered the mineral in 1883.

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MAJORITE forms under the extreme pressure that occurs 250 miles (400 km) or more beneath the earth’s surface or from the shock of a meteorite impact. It’s a dark purple form of Garnet that was discovered in 1970 in the Coorara meteorite near Eucla, Western Australia. The species is named after Alan Major who researched high-pressure Garnet formation. Has similar formation to the apple green Moldavite collected from around a metor strike in the Czech Republic.

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TAAFFEITE is a mauve to purple to red stone named after Bohemian-Irish gemologist Edward Taaffe who discovered the first one from a box of Sri Lankan spinels in 1945. The stone displayed a double refraction which was uncharacteristic of spinel. If you could round up all the faceted taaffeites currently in existence they would fill about half a cup. Of the rarest red variety there are fewer than ten specimens.

.MUSGRAVITE is a species chemically and optically similar to Taffeite, but is even rarer. Facetable musgravite was first reported in 1993 and as of 2007 there were eight such specimens. The mineral was discovered in 1967 at the Musgrave Range in South Australia, but has since then turned up in Greenland, Madagascar and even Antarctica. It’s not unlikely that some stones thought to be taaffeites by their owners are actually musgravites. Micro-Raman spectroscopy, which uses a green laser, can quite handily distinguish the two.

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BENITOITE is found only in San Benito County, California. The stone is a strong blue with a dispersion similar to that of diamond, and fluoresces an intense blue-white under UV light. The largest faceted Benitoite weighs 15.42 carats, but stones over one carat are rare. In 1974 someone stole a flawless 6.52-carat pear-shaped specimen from the Zurich airport and it’s still missing. In 1985, Benitoite was designated the state gemstone of California.

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PHOSPHYLLITE is a rare mineral composed of hydrated zinc phosphate. Its name derives from its chemical composition (phosphate) and the Greek word for "leaf", phyllon, a reference to its cleavage. It is highly prized by collectors for its rarity and for its delicate bluish green colour. Phosphophyllite is rarely cut because it is fragile and brittle, and large crystals are too valuable to be broken up. The finest Phosphophyllite crystals come from Potosi, Bolivia, but it is no longer mined there. Other sources include New Hampshire, USA, and Hagendorf, Bavaria, Germany. It is often found in association with the minerals Chalcopyrite and Tripholite.

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The above listing appears to be based on the hardest to find, finding sizes to facet and somewhat on pricing. There are other listings of the 10 rarest gemstones based solely on price, hardest to find, exotic and lack of availability. The following list is based on a 2008 cost per caret. Please note several are repeated from the above list.

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Jadeite $3+ million/caret

Red Diamond $2-2.5 million/caret
Serendebite $1.8-2 million/caret
Blue Garnet $1.5 million/caret
Grandidierite $100,000/caret
Painite $50-60,000/caret
Musgravite $35,000/caret
Red Beryl $10,000/caret
Black Opal $2,500/caret
Jeremejevite $2,000/caret
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some even add Tanzanite to this list at $1,800-2,200/caret.
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And then we must not forget the most popular gemstone: which by it's pricing would quickly make one think it is rare:
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DIAMONDS, in general, Diamonds are not at all rare, but controlled pricing keeps the price high. The De Beers Company would prefer you didn’t know, but annual world production of gem-quality Diamond exceeds sixty million carats. This equals twelve metric tons and would fill about 145 bushel baskets. Consider this the next time you pony up a few thousand dollars for an engagement ring stone. However, colored Diamonds, called fancies, can be genuinely scarce. About one carat out of every 10,000 sold is a fancy. These shades include yellow, green, blue, orange, brown (“champagne”), purple, gray, black (called carbonado, recently shown to be meteoric), milky white, pink and red. Red is by far the rarest.

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Thanks to several gemology friends for information and pictures of the rare gemstones, although still missing a couple pictures.
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