Category: Gemmology (Page 1 of 2)

Fine Harlequin Opal — A Fine Black Opal sold for $13,000 at Auction

Opal: A Spectrum in a Gem

April 8, 2020 / Duncan Parker

Black Opal in a Belle Epoque Necklace
Offered at auction June 2020

Opal has fascinated people for thousands of years. Its hypnotic iridescent spectrum of colours flash as the gem moves. The colours in an opal float mysteriously from within its translucent depths.

Sources

While many people think of opal as a distinctly Australian gem, the ancient Romans were very enthusiastic about opal. Pliny the Elder, a scholar in ancient Rome, 2000 years ago, wrote that opals “combine…the brilliant qualities of the most valuable gems…all combined together in incredible brilliance…they defy description”1… . Opals known in ancient Rome were not from Australia, they were likely from what is now known as Slovenia.

These days, most opal in the market is from either the classic sources in Australia, or Mexico (for “fire” opal), or from the relatively new source in Ethiopia.

Opal is known under many different variety names. These names usually describe the body of the opal. The body colour is the appearance the gem has before you take the flashes of colour into consideration.

Opal Types

Black opal has a black to dark grey body colour. The dark background shows the flashes of colour to their best effect. Black opal from Lightning Ridge, in Australia’s New South Wales, is the most famous. Other sources do produce opal with a dark background, often dark grey, or from Ethiopia it’s sometimes dark brown. Often black opal is opaque. Black opal is the most rare and valuable opal.

Semi-black opal has a dark body colour, while not quite “black” it’s next in darkness. Semi-black opal can come from Lightning Ridge and from other sources, including Mintabie in South Australia.

White opal has, as you might guess, a white body colour. The flashes of colour are seen against a light background. The best known source for white opal is a town in South Australia called “Coober Pedy”.

Fire opal has an orange or red body colour, like flames in a fire. The most famous source is Mexico. Often fire opal has no flashes of colour at all, but it is still prized for its near-transparent appearance, and is often faceted, with small flat faces, like a diamond or other gems.

Crystal opal is often colourless, and very close to transparent, but with a “play of colour”, those famous flashes of colour that makes opal so desirable. In a crystal opal, the colours are particularly mysterious as they float in the clear colourless gem.

Colours of Flashes

There is a hierarchy of desired colours in opal. Flashes of red are the most desired, and if you have red, you’ll usually find the other colours present in the opal’s flashes. Some opals may show just green and blue colours, and can be quite lovely.

Patterns

Pattern of colours is another thing we note. One pattern, of geometric blocks of colour flashes is called “harlequin”, is rare, and highly desired.

“Rolling flash” is a pattern of play-of-colour that has areas of colour that may roll over large parts of the surface of the opal, changing colours as the opal is moved.

A common pattern is called “pinfire”. Opals that have this pattern show tiny dots of colours scattered and shifting as the viewer’s angle changes.

One of Queen Victoria’s favourite gems was opal, and during her long reign, several of the Australian localities were opened up by the colonists. The discoveries of opal in Australia meant that there was a renewed interest in opal in Europe, in the nineteenth century.

The discovery of opal in Ethiopia has produced a new source of striking and beautiful gems. The opals from this African nation range from crystal opal to black. The film Uncut Gems features an Ethiopian black opal.

(1: Pliny: Natural History Books 36-37, Translation by D.E. Eicholz, Loeb Classical Library, Harvard University Press, Cambridge Mass, 1962)

Burma: What Does It Mean for Gems?

May 23, 2018 / Duncan Parker

Burma

(Also Known as Myanmar)

Burma Ruby and Diamond Ring Sold, November 2017, $22,000

Burma, it’s a name that evokes images of great treasures to anyone who knows about gemstones.

Now known as Myanmar, the country is still referred to as Burma by many people.

The country of Burma is in Southeast Asia, bordering India, Bangladesh, China, Laos, and Thailand. Several of these countries are known for their gem wealth. However, this one country stands out as a shining light among the great gem sources.

The Most Famous Rubies in the World

Burma is historically known as the source of the finest rubies in the world. These remarkable red gems are found in several sources, but no rubies are as eagerly sought-after as those from Burma, the most famous of gem sources.

The finest Rubies from Burma have an intense to vivid tone of slightly pinkish red colour, and it can be a colour that is remarkably eye-catching. Of course, variations in colour can come from any source, but Burmese rubies are very fine, on average, and are reminiscent of a hot coal.

Other countries in Asia are noted sources of ruby. Neighbouring countries of Thailand, Cambodia, Laos, and nearby Vietnam have all produced many beautiful rubies. However, these nearby sources don’t have the same fame and history. Also, none of the other sources produces rubies of quite the same vivid colours.

Additionally, a number of countries in Africa have been producing rubies, but still Burma rings on the lips of gem lovers.

Jade

Burma (Myanmar) jadeite jade and diamond ring, Lot 354, offered in the Important Jewels Auction, June 2018

Jade is a gem that is famous for its luminescent green colour. The word “Imperial” is often given to the richest, strongest green found in the gem known as jadeite jade.

Two types of gem that are called jade: Jadeite jade and nephrite jade. The rich and vibrant green of the finest jadeite from Burma is unmatched. There really is no other source for this most precious jadeite jade. While the other type of jade, nephrite, is found in many countries around the world, Canada is a major exporter of this other type of jade. Nephrite jade has a lower intensity of colour and often has a greyish green colour. Historically, for centuries, jadeite jade of a bright green colour and a high degree of translucency has been a gem most highly prized in China. and other countries.

Sapphire

6.44 carat Burma (Myanmar) sapphire offered in June 2018 Important Jewels Auction

Burma is a source of very beautiful sapphires, and has been for a very long time. The only sapphire more desired is one from Kashmir, but Kashmir hasn’t been mined for decades, making sapphires from Kashmir extremely rare. So, these days, Burma produces some of the finest sapphires in the world. The colour of a Burma sapphire is often a rich and very attractive blue.

Burma is a key gem source, and remains that way after centuries of production, it is highly important to this day. The country is a most highly desired source for the most important gems in the world. Being from Burma adds to the value of a gem when compared to similar gems from other countries.

We are very fortunate to have the consignments that allow you to purchase Burmese gems at Dupuis auctions on a regular basis.

Inclusions in Gems, a view of the inner world of gemstones

January 28, 2015 / Duncan Parker

INCLUSIONS IN GEMS

A view of the inner world of gemstones

“Three phase” inclusions in a emerald

The inner world of gems is fascinating. Inclusions found within gems are the things that get gemmologists hooked on this science. We love to look at the fascinating crystals, growth features and strange structures in gems. Many inclusions are crystals of minerals.

Emerald:

An emerald may be identified as natural if it has three-phase inclusions (a solid, a liquid and a gas; with the solid being a crystal of some kind, and the gas being a bubble that sometimes can move around in the liquid). Emeralds originating from Colombia are particularly noted for three-phase inclusions.

Diamonds:

Diamonds can have lots of interesting inclusions, sometimes another diamond inside a diamond, but often a crystal of an entirely different mineral. We often see reddish garnet crystals in diamonds.

Diamond with bright red garnet inclusions

Sometimes we might see several different colours of inclusion in the same diamond. This one has an inclusion of garnet that is orange brown colour and another that is green and is possibly diopside:

Diamond 0.33ct orange brown and green crystals

Diamond with orange-brown garnet, and green (possibly diopside) crystal inclusions

Sometimes we don’t know what an inclusion is, being inside another gem makes it hard to get at, and complex to test, but it’s still really interesting to look at. This orangish inclusion in the corner of a diamond looks a bit like a lighthouse floating in space, or a Dalek (ask a Doctor Who fan). It isn’t either of those things, it’s a mineral, however, we’re not sure what that mineral is.

Pinkish brown crystal inclusion in a diamond

There are naturally occurring fractures in gems, they are often called “feathers”. I guess the reason for calling them “feathers” is because they can sometimes look like that. This one in a diamond really looks like a feather:

Diamond inclusion feather incident light

“Feather” in a diamond

Sapphire:

Sometimes we see inclusions of one colour mineral in another colour of gem. Here is a red crystal of a mineral called rutile in a blue sapphire. If it is placed just right (or wrong) the colours can combine to create a new colour to the eye (more purplish, in this case, with red mixed with the very nice blue)

Blue sapphire with a red rutile crystal inclusion

Emeralds can have some very interesting inclusions, apart from three-phase ones. Here we have opaque cube shaped yellow metallic pyrite inclusions that are of a size that can be seen with the naked eye. Emeralds usually have eye-visible inclusions of some kind.

Beryl emerald with pyrite inclusions 8 copy

Emerald with pyrite cube crystal inclusions

Quartz:

Among the most commonly seen gems in the world are those of the quartz family. There are so many varieties, colours and textures of quartz found all around the world, and each can have distinctive inclusions. Often, quartz is a modestly priced gem, and specimens with noticeable and desirable inclusions are often available. This example of “rock crystal” quartz features dark reddish-black needle-like inclusions, scattered like pick-up-sticks.

Rock crystal quartz with scattered needle-like tourmaline crystals

Inclusions are such an interesting feature of gems, and for any gemmologist with a microscope or a loupe, they’re among of the most fascinating features of a gem. While most people tend to think of inclusions in a negative way, they make gems unique, and give each its own fingerprint, providing hours of distraction for a gemologist, or anyone else.

ABC of Gems

December 12, 2014 / Duncan Parker

A collection of many different gems in a bracelet

There is a beautiful and interesting gem for almost every letter of the alphabet. We all had an A B C book when we were little, why not carry this forward into our adult life (or our continued childhood) with an ABC of Gems? (All of the items featured in the photographs in this ABC of Gems have been offered in Dupuis Fine Jewellery Auctions, with the exception of those at U, V, W, X, and Y).

Amethyst, the February birthstone, has a very long history, and is a lovely violet gem, here is an example of some violets carved from amethyst:

Amethyst flowers

Beryl is a gem found in many colours including blue (aquamarine), and green (emerald). These golden beryls are specially cut and matched for this brooch:

A fan of custom cut golden beryls

Coral is found in the Mediterranean Sea, and forms in branch-like shapes with red, orange and pink colours:

Coral stems on a flower brooch

Diamond, the world’s best known gem, is the hardest substance in nature. It forms deep in the earth, and is carried to the surface by volcanic activity. We need to move tons of rock to extract a single carat of this exceptional gem. Diamond is the birthstone for April.

diamond solitaire pendant 9.38 carats

Emerald is a green gem, with a very long history from “Cleopatra’s emerald mine” in the ancient world, to the famous source of emeralds in Colombia. The fresh spring-like green of an emerald makes it a calming and refreshing gem. Emerald is the birthstone for May.

Emerald and diamonds in a ballerina ring

Fibrolite, is a less common gem, and is often found exhibiting a clear and sharp “cat’s eye”. The colour is often grey.

Fibrolite cat’s eye ring

Garnet is a gem found in every colour of the rainbow. Best known as a brownish red gem, garnet is also found in rare yellowish green Demantoid, and brilliant green Tsavorite. Garnet is there birthstone for January.

Very fine tsavorite garnet

Hematite is a bright, shiny grey metallic gem, often used as beads, or in men’s jewellery.

Hematite in cufflinks and tie tac by Schlumberger for Tiffany

Ivory is a gem principally from the tusks of elephants. There are some beautiful gems and carvings made from ivory. It is from an endangered species, trade is restricted, and is no longer offered at auction by Dupuis.

Ivory netsuke carving

Jadeite jade is a gem principally found in Myanmar (formerly Burma), and is most prized in a rich uniform green colour and with a high degree of translucency.

Fine jadeite jade and diamond ring

Kunzite is a pink to purple gem found in the United States and Afghanistan, and it is named after a gemologist and friend of Louis Comfort Tiffany, George Kunz.

Kunzite and diamond ring

Lapis lazuli is a rich blue ornamental gem. The most famous source is Afghanistan, and the gems from there can be a vivid blue unlike any other gem.

Lapis Lazuli and gold necklace

Moonstone is a mysterious gem that has a silvery “moon” that floats around as the gem moves.

Antique moonstone necklace

Nephrite jade is one of two gems named jade. Most notably in an olive green colour. It is found in countries around the world, including in Canada’s British Columbia.

Nephrite jade leaves and coral beads in a brooch

Opal is famous for its flashes of the colours of the spectrum. It is most valuable if it has bright flashes of all colours of the spectrum. The best known source is Australia. Opal is the birthstone for October.

Black opal and diamond ring

Pearl was likely used as an ornamental gem before almost anything else. Pearls were the first “free prizes” in the history of food. Biting into an oyster and finding a pearl was a pretty nice bonus for our ancient ancestors. Natural pearls are very rare today, but are still sometimes found. Pearl is the birthstone for June.

Cultured pearl necklace in a rainbow of colours

Quartz, truly an ABC of gems in itself, is a gem that has colours and textures to suit all styles and tastes. Quartz has been found in ancient jewels, and it is found in every continent. Amethyst is the most precious variety, Citrine follows closely behind, carnelian is a translucent orange variety that has been used for thousands of years.

Citrine bracelet

Ruby is a red gem, most famously found in Myanmar (formerly Burma). it is the birthstone for July, it is associated with Power and passion. The inner glow of a fine ruby is unlike any other gem. Ruby is the birthstone for July.

Ruby and diamond ring, “pigeon blood” colour

Sapphire is another ABC of gems because it can be any colour except red (red colour of this mineral is called ruby). The most sought after sapphire is a rich velvety blue colour that is now depleted, but was found in Kashmir until the mid-20th Century. Currently sapphires are found in Myanmar (formerly Burma), Sri Lanka, Madagascar, Thailand, Cambodia, Australia, and even in Canada’s Baffin Island. Other highly desired colours are pink, and yellow. Sapphire is the birthstone for September.

Antique sapphire and diamond ring

Topaz is best known in two main colours, yellowish orange (sometimes called “imperial topaz”), and blue. but it is found in pink, colourless, and others too. Found in many countries including Brazil and Russia, it is the birthstone for November.

Topaz necklace

Uvarovite is a variety of garnet that usually forms in tiny crystals, sometimes used as “drusy” (clusters of tiny crystals covering a surface) in finished jewellery. Very rarely it is large enough crystals to facet (but still very small)

Uvarovite garnet (0.50mm in diameter)

Vulcanite was produced in the 19th Century as an inexpensive alternative to the organic gem, jet. Vulcanite is an opaque black vulcanized rubber compound that is hard, and was usually moulded into what appeared as carved forms.

Vulcanite cameo mounted on mother of pearl

Welo Opal is named after its source in Ethiopia. It is opal from a new source, and is noted for bright colours.

Welo opal (rough – unpolished)

X-Ray (some letters in an ABC of Gems are more difficult) Used in the identification of pearls, X-Ray testing can assist in separating natural pearls from cultured pearls. X-rays are also used in separating diamonds from ore at diamond mines.

X-ray of cultured pearls showing mother of pearl beads inside the cultured pearls

Yttrium Aluminium Garnet (YAG) is a laboratory grown material originally used as a diamond simulant, it is now produced in many different colours. It is hard and durable, and serves as an inexpensive imitation of other gems.

Laboratory grown YAG

Zircon (we can finish an ABC of Gems with a genuine gem): Zircon is a natural gem that is found in yellow, brown, green, blue and colourless. Zircons can be very pretty and dispersive, showing sparkles of colour you might expect in a diamond.

Zircon and diamond ring

Natural Pearls, rare beauties of the natural world, and how we identify them

June 27, 2014 / Duncan Parker

Natural pearl necklace: Lot 261 in Dupuis Spring 2014 Auction, sold for $60,000 http://bit.ly/DUPUIS-LOT-261

Natural pearls are a very rare thing. They have grown by accident, and are the product of incredible good fortune. Once upon a time people would dive, time after time, into the ocean, searching for the one elusive “oyster” that was bearing the extraordinary gift of a pearl. These natural pearls are very rare, and highly desired today.

The translucency of the pearl material called “nacre” gives natural pearls a radiance that is unlike anything else. This translucency allows light to penetrate the natural pearl and produces reflection of light and iridescence, often in a rainbow of colours, sometimes referred to as “orient” or “overtones”.

What gives value to a pearl is its size, the smoothness of its surface, the roundness of its shape, its body colour, the colours of the “overtones” seen in each, and the matching of the pearls if there are more than one.

One of the ways that we distinguish natural pearls from cultured pearls is that cultured pearls usually have a bead of mother of pearl inside, and a layer of the pearl material called nacre laid on by the mollusc, or “oyster” on the outside, and natural pearls are layers of nacre all the way to the centre, with no bead.

We can X-ray pearls to detect a bead, or sometimes we can look down the drill hole to detect a bead. In natural pearls we often see layer after layer all the way to the centre of the pearl. Following are some images of the layered structure seen in some of the natural pearls in the necklace shown above.

Looking down the drill hole of a natural pearl

The layered structure seen down the drill hole in a natural pearl

Diamond Shapes

June 26, 2014 / Duncan Parker

Diamond Shapes

12.37 Carat Diamond Crystal

Diamond shapes are widely varied. There is a reason; a diamond crystal is like so many products of nature; slightly variable within a general form. A perfect diamond crystal is an octahedron, in the form of a four sided pyramid pointing up, on top of a four sided pyramid pointing down, in other words: A square shaped eight sided form.

If diamond crystals are square, why are so many cut and polished diamonds in a round shape? The earliest diamonds in jewellery were uncut, and the earliest cut diamonds were actually square, with a cut-off top, like opening a hard boiled egg, this was called a table cut.

Table Cut Diamond in a ring

In the 18th Century, diamond cutters developed a more sophisticated cut to reveal better and brighter sparkle in a diamond. This cut we call “old mine cut”, and prevailed for the century that Brazil was the main world source of diamonds. Old Mine cut diamonds are rounded square forms, but still reflect the original squarish crystal shape.

Old Mine Cut Diamond

Back in the second half of the 19th Century, diamond cutters worked out that a round shape could produce a diamond of uniform brilliance and sparkle, this round diamond took the next step past the old mine cut, and is called the old European cut.

Old European Cut Diamond: Lot 113, Dupuis Spring 2014 Jewels Auction http://bit.ly/DUPUIS-LOT-113

In the early years of the 20th Century, an engineer, Marcel Tolkowsky, calculated the shape and exact proportions and angles to create the most brilliant, sparkly diamond, and in 1919, published his findings. We never looked back, and his work still stands as the basis for the modern round brilliant cut diamond.

Round Brilliant Cut Diamonds: Lot 286 in the Dupuis Spring 2014 Jewels Auction http://bit.ly/DUPUIS-LOT-286

That is the beginning, we have all sorts of other shapes of diamond cut. Why do we have them? First: People have different tastes, so not everyone wants a round diamond, and a round diamond doesn’t suit everyone or every occasion. Second: diamond crystals aren’t all exactly the same. While crystals of diamond are identical in their composition and structure, they might have different outward appearances. Some might be more rounded, some stretched out into a rectangular form, some might come out of the ground as fragments. The diamond cutter will assess each crystal, and will work out how to make the most of it. If a crystal has an unusual form, that may dictate the final shape of the polished gem.

Pear shaped diamond pendant: Lot 388 in the Dupuis Spring 2014 jewels sale. Sold for $509,000 http://bit.ly/DUPUIS-LOT-388

Popularity of diamond shapes may be driven by fashion. One year marquise shaped diamonds may be a favourite, and another year a pear shape may be in vogue. Round diamonds remain the most popular shape, and any shape other than round is called a “fancy shape”. Generally, fancy shape diamonds are cut because the rough diamond would produce the best looking gem and the most advantageous financial result that way.

The diamond cutter’s job is two fold: Make the most beautiful gem, and don’t waste any of the precious diamond. If that means making a heart shape, then that is what will be.

Following are examples of some of the more regularly used diamond cut shapes.

Heart shaped diamond: Lot 517, Dupuis Spring 2014 Jewels Auction

Rectangular radiant cut diamond: Lot 310 Dupuis Spring 2014 Jewels Auction

Princess cut diamonds: Lot 691, Dupuis Spring 2014 Jewels Auction

Trilliant cut diamonds: Lot 669, Dupuis Spring 2014 Jewels Auction

Rectangular cushion shaped diamond: Lot 383, Dupuis Spring 2014 Jewels Auction

Emerald cut diamond: Lot 342, Dupuis Spring 2014 Jewels Auction

Birthstones in fine jewellery?

May 15, 2014 / Duncan Parker

We all have preferences in our choice of gemstones, but one thing we might feel more connected to is our birthstone. Birthstones are gems that have been chosen for astrological reasons and are associated with certain months. In almost every auction, we find that there is a full representation of the traditional Western birthstones. Looking through these birthstones, people might be pleased to find that there are diverse choices available. Birthstones are not limited to family rings.

January: Garnet: While we tend to think of Garnets as having a narrow palette of brownish red colours, there is a broad spectrum available, green varieties such as the very rare Demantoid being the most valuable, the most famous source of demantoid is the Ural Mountains in Russia.

An Antique Demantoid Garnet and Diamond Bee Brooch: Lot 50, Spring 2014 sale

February: Amethyst is a purple variety of quartz, and is only one colour, but a beautiful colour. Amethyst is very popular today, and was also very popular in the Victorian period. In Ancient Rome, an amethyst dropped into a glass of wine was thought to prevent inebriation. It is the Provincial gemstone of Ontario, Canada.

Amethyst, Turquoise and 14K Gold Ring: Lot 462, Spring 2014 sale

March: Aquamarine is a greenish blue to blue gem. Its name derived from Latin, suggests the colour of water (aqua) and sea (marine). The gem ranges from pale to intense, and is most treasured in a strong blue colour. It most famously originates in Brazil.

Aquamarine, Diamond and 18K Gold Ring: Lot 485, Spring 2014 sale

April: Diamond is the best known gem in the world. There are more legends and histories revolving around diamonds than all other gems combined. For thousands of years, India was the only known source of these gems, until the 18th Century when they were discovered in Brazil, and the 19th Century when they were discovered in South Africa. The 21st Century sees diamonds being mined in Australia, Canada, Russia, Namibia, and Botswana, among other countries. Canada is the 3rd largest diamond producer in the world. It is rare to see a diamond as fine as Lot 388, the pear shaped 9.35 carat, F colour, VS-1 clarity gem in the Spring 2014 sale.

A Diamond Solitaire Pendant: Lot 388, Spring 2014 sale

May: Emeralds are the green variety of the mineral beryl. Historical myth states that Emperor Nero looked through an emerald monocle at gladiator fights and during the burning of Rome. Emeralds are a soothing gem. They naturally have visible inclusions, sometimes referred to as “jardin” (garden from French). It is truly rare to find an emerald as beautifully coloured and as clear to the eye as Lot 49 in the Spring 2014 sale. It is truly an exceptional gem.

An Emerald and Diamond Ring: Lot 49, Spring 2014 sale

June: Alexandrite is a fascinating gem. It appears one colour in one kind of light, and another colour in another kind of light. The gem’s name originates from the time of its discovery in Russia in April 1834 on the birthday of the future Tsar, Alexander II. Its colours from Russian sources are famously green in sunlight, and red in candlelight, or incandescent light, and red and green were the Russian national colours. Some specimens from other sources are purple to blue, but the colour change is fascinating either way.

An Alexandrite and Diamond Ring: Incandescent light (left), daylight (right): Lot 123, Spring 2014 sale

Pearls are an alternate birthstone for June. Natural pearls are very rare, and occur purely by an accident of nature. Most pearls we see are cultured, and while the outer surface is exactly the same on the cultured and natural pearls, the cultured pearls are helped along, usually by placing a mother of pearl bead inside the mollusc, and it then coats it with nacre (pearl material) for a few years. Natural pearls are the nacre material through to the centre, and may have taken many years to form. Lot 365 is a very rare and unusually large pearl that has an independent report describing it as natural.

A Natural Pearl, Diamond and Platinum Brooch (14.74mm diameter pearl): Lot 365, Spring 2014 sale

July: Ruby is a red gem, a passionate colour for a passionate gem. The finest colour is brilliantly pure red, and the gem most commonly has inclusions visible to the eye. The most famous source of ruby is Myanmar (formerly Burma). Ancient literature suggests that someone who dreams of a ruby will have good fortune. It would certainly be good fortune to be the highest bidder on the exceptionally red Lot 355. While the vast majority of rubies have been heated to improve their colour, this ruby is untreated.

A Ruby and Diamond Ring: Lot 355, Spring 2014 sale

August: Peridot is one of those gems that is only available in one colour. It is a yellowish green, and most often is clean to the eye. Historically, the most famous source of peridot is the “Serpent Isle”, in the Red Sea. The gem was used in ancient Egypt, and was only to be used by those of the highest rank in society. It was said to dispel the dark things of the night. Today, Pakistan and Myanmar (formerly Burma) are sources of important peridots. This ring by British designer Theo Fennell makes wonderful use of the colours of peridot and topaz in combination.

A Peridot and Blue Topaz Ring: Lot 280, Spring 2014 sale

September: Sapphires may be any colour except red (ruby is the same mineral, but is the red colour). Sapphires famously originate in Kashmir, Sri Lanka, and Myanmar (Burma), but are also mined in Madagascar, Australia, Thailand, and other countries. Blue is the colour most associated with sapphire, and the finest colour is a bright medium blue sometimes referred to as “cornflower blue”. Sapphire is considered to be a soothing gem.

A Sapphire and Diamond Ring: Lot 265, Spring 2014 sale

October: Opal is an unusual gem. Opals may have a number of different appearances, and may be clear and colourless to black or orange or red in their body colour, and are valued for the flashes of colours that shimmer about on their surface when they move in the light. Queen Victoria loved opals. The most famous source of opal is Australia, with the most precious, black opal, originating principally in a small town called Lightning Ridge.

A Black Opal, Diamond and Platinum Ring: Lot 252, Spring 2014 sale

November: Topaz is a gem found in numerous colours. The golden yellow colour is best known, while pink is rare. Blue in various shades is widely available, often produced by treating colourless topaz. Historically, citrine and smoky quartz have mistakenly been referred to as topaz. Brazil is the most famous source for topaz. With a slight overtone of pinkish, golden yellow topaz is often referred to as “imperial” topaz.

A Topaz and Diamond Pendant: Lot 24, Spring 2014 sale

December: Tanzanite has recently been adopted as a Birthstone for December. Introduced to the world by Tiffany, Tanzanite made its debut in 1967. This lively purplish blue gem is found principally in one source not far from the base of Mount Kilimanjaro in Tanzania, the country after which it is named.

Unmounted 9.29-Carat Oval Tanzanite: Lot 491, Spring 2014 sale

A Pearl is a Pearl, isn’t it?

May 6, 2014 / Duncan Parker

Belle Epoque Pearl and Pendant: Lot 195, Spring 2014 sale

When we think of a pearl, we tend to think of a round white shiny object that comes from an oyster of some sort.

A pearl may well fit that description, but there are so many variations available, it is quite surprising.

Historically, a pearl is a roundish to randomly shaped gem that has formed accidentally in a shellfish, usually a bivalve. A bivalve is a shell fish (mollusc) that has a two part shell, like an oyster, a clam, or even a quahog.

Hold on… QUAHOG?, what’s that? A quahog (usually pronounced “cohog”) is a shellfish found along the Eastern Coast of North America and particularly around Cape Cod and New Jersey (along the Jersey shore). These clams are an important food source, and which very rarely will produce a lilac colour pearl. Lot 119 in the June 22, 2014 Dupuis sale features one of these rare and unusual pearls, measuring 10.3mm in diameter, and estimated $1,500-$2,500.00 with a diamond on a gold stick pin. The catalogue will be available shortly at www.dupuis.ca

Antique Natural Pearl and Coloured Diamond Stickpin with a Quahog Pearl: Lot 119, Spring 2014 sale

We do occasionally find a pearl in a univalve mollusc, too. A univalve is a mollusc that has a one-part shell, like a snail or perhaps a conch, from the Caribbean. Conch pearls are usually pink, and are also very rare and valuable. Lot 660 in the spring sale features a bright pink conch pearl, estimated at $1,000-$1,200

Conch Pearl Diamond and Platinum Ring: Lot 660, Spring 2014 sale

With the development of pearl culturing in Japan around 1915, the pearl industry changed forever. What we think of as a pearl today is a cultured pearl.

A cultured pearl is still produced by these natural gem-makers of the sea (or lake or river), but humans help out by placing something inside the molluscs to start the process of pearl growth.

Now we have pearls being cultured in the ocean, with the traditional cultured pearls grown in cooler waters such as those around Japan, the larger South Sea cultured pearls grown in warmer waters and in larger molluscs, black cultured pearls cost famously grown around Tahiti, and many shapes and sizes of cultured pearls grown in the freshwater (or “sweet water”) of lakes and rivers, particularly in China.

Freshwater cultured pearls can grow in very large sizes and in many unusual shapes and colours. The upcoming auction Dupuis will be featuring a few necklaces of large and interesting freshwater cultured pearls. Freshwater cultured pearls make a great statement for a remarkably modest price. Lot 407 in the Spring sale features huge freshwater cultured pearls, and is estimated at $1,400-$1,600.

Still, natural pearls remain rare and highly desirable. We really see a lot of interest in natural pearls because they are not replaceable. In the Spring 2014 (June 22) sale there are several notable natural pearl jewels. Among the natural pearls in the sale are one brooch, lot 365, with a notably large, 14.74mm natural pearl, and a necklace, lot 277, with three strands of pearls (including a single cultured pearl).

Natural Pearl Diamond and Platinum Brooch: Lot 365, Spring 2014 sale

Antique Natural Pearl Sapphire and Diamond Necklace: Lot 277 Spring 2014 sale

Pearls are probably the original gem, because they are ready to use straight out of the shell, and one can imagine an early cave dweller with a broken tooth having enjoyed a meal of oysters and carrying the reward of a beautiful lustrous pearl.

Modern Cameos

February 11, 2014 / Duncan Parker

I have just returned from the gem shows at Tucson Arizona. Tucson is the place where the whole gem and jewellery world gathers to who off what is new, interesting, and happening. I go there to learn what is in the market, to give lectures, and participate on specialist panels.

I was struck by the work of the Italian cameo worker Vincenzo Imposimato. The work of this artist is very distinctive. Even items that depict conventional images show unique elements, and most are entirely distinctive.

The designs are unlike others that I have seen. It is rare for cameos to be pierced with openings from front to back.

These carvings will make for very distinctive jewels.

At auction, we regularly feature cameos, and many of them are artist pieces that are unique representations of their own time. Recently, Lot 460 in the Spring 2013 sale featured a very fine art cameo by Nino Ammendola.

Colombian emerald crystals and jewels

January 23, 2014 / Duncan Parker

Emerald Pendant at Dupuis Auctioneers

Colombian emeralds tell their stories well. The inclusions are so distinctive that they really can’t be from anywhere else. These hexagonal crystals have recently come from the Chivor mine in Colombia. They have “three phase” inclusions, with a solid, a liquid and a gas. The solid is a crystal and the gas is a bubble, and the bubble and crystal are in a liquid in a completely sealed off space in the crystal. I don’t know how long it has been there, but I do know where it came from. Emeralds from elsewhere don’t have these, and they are even identifiable under high magnification in finished gems such as lot 209 from the fall 2013 Dupuis auction. Visit www.dupuis.ca for upcoming news on the spring 2014 auction.

“three phase” inclusions

Category: Gemmology (Page 1 of 2)

Opal: A Spectrum in a Gem

Burma: What Does It Mean for Gems?

Burma

(Also Known as Myanmar)

The Most Famous Rubies in the World

Jade

Sapphire

Inclusions in Gems, a view of the inner world of gemstones

ABC of Gems

Natural Pearls, rare beauties of the natural world, and how we identify them

Diamond Shapes

Birthstones in fine jewellery?

A Pearl is a Pearl, isn’t it?

Modern Cameos

Colombian emerald crystals and jewels

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