Tag Archives: Black Opal

The Making of a Masterpiece VI (Part 2)

The finished pendent, steps in making follow.

The finished pendent, steps in making follow.

The wing is constructed of separate elements to give it maximum definition. Here an individual "feather' has been cut out, drilled for the gem and is prepared to be domed.

The wing is constructed of separate elements to give it maximum definition. Here an individual “feather’ has been cut out, drilled for the gem and is prepared to be domed.

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Here goldsmith Michael Corneau uses a steel punch to curve a single feather of the bird's wing.

Here goldsmith Michael Corneau uses a steel punch to curve a single feather of the bird’s wing.

Ancient Technique of Sand Casting:

Truly handmade jewelry is made in the ancient manner using the metal itself.

Modern commercial and some so-called handmade pieces are actually carved in wax and then cast using the cire perdue or lost wax process.  The more ancient method is sand casting.  The approach is similar, a model is made and it is impressed into a crucible.  In each case the molten gold is poured into a vacancy.  Once a mold is made, lost wax can be used to produce multiples.

The total time required for Michael Corneau to produce the Peacock Pendent was 212 hours.  This did not count, of course, the time spent developing the concept, discussion and selection of gemstones.

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PouringGoldSand

Sand casting the peacock’s body: Molten gold is poured into the depression made by removing the model from the sand.

Setting the gems: Once the feathers have been dapped out and soldered together and the cast body has been finished and soldered to the tail, gem setting can begin, the method is known as thread and bead setting.Peacock Pendant: Micro view, all gems set.

Setting the gems: Once the feathers have been dapped out and soldered together and the cast body has been finished and soldered to the tail, gem setting can begin, the method is known as thread and bead setting.Peacock Pendant: Micro view, all gems set.


by Richard W. Wise, G.G., A.S.G. ©2012 all rights reserved.

Quality Grading Opals, The Toughest Challenge of them all

by Richard W. Wise, G.G.

©2011

Three black opals showing two tones of body color.  The Australian valuing system recognizes nine degrees of body tone.

Three black opals showing two tones of body color. The Australian valuing system recognizes nine degrees of body tone. The gems at right would be graded N1, the oval to the left N3. Photo: Cody Opal

Over the past decade it has been my privilege to get up close and personal with some of the world’s most fabulous opals.  My love affair with this idiosyncratic gem began in 1991 with a visit to the opal fields of Queensland.  At that time I was researching an article that would eventually be featured in Gems & Gemology, the journal of the Gemological Institute of America, under the title: Queensland Boulder Opal.

Queensland, like most of the Australian outback, has come to embody the frontier spirit,  the ethos of America’s old west.  Strong solitary loners, men of few words with names like Texas Jack and Silk Shirt Joe, labored under almost unbelievably harsh conditions, nourished by the stubborn belief that sooner or later they would hit pay dirt.  It took just a few days days with the guidance of the late Vince Evert to realize that even in the waning days of the 20th Century, much of that spirit lived on.winton_map

With Evert as our guide, the adventure began when our Piper Apache approached a bumpy dirt airstrip that had been carved out of the arid plains on the outskirts of  Winton (marked w/red dot), a frontier town 350 miles into the Queensland outback.  The Evert family are among the town’s most substantial citizens.  Proprietors of a gift shop and the town’s only outdoor theater, they are also one of the area’s largest mining operations–entrepreneurs and opal cutters.   It was Vince, dressed in khaki with a plain brimmed Akubra hat—Australia’s five gallon version of the ten gallon hat—who stood waiting as our single engine plane taxied to a dusty stop.

It was a sunny day in early March, the temperature hovered around 120°F.  The outback is basically desert, and water is drawn from bore holes, wells that reach as much as 3,000 feet down below the cracked brown earth; the water comes up hot and stinking of sulfur.

Describing Opal:

Opal nomenclature can be a bit tricky.  In the old days unwieldy and confusing terms such as white, crystal,  semi-black, semi-black crystal and black were used.  The new Australian system of classification now recognizes nine levels of body color or body tone (N1-N9).

Opal body tones, there are nine basic grades and opal gets noticeable lighter in body color as you go down the scale.

Figure 1: Opal body tones, there are nine basic grades and opal gets noticeable lighter in body color as you go down the scale. Photo: Cody Opal

Body color is the background color, the color of that part of the opal which shows no chromatic fire (play of color).  Opal classifications are based strictly on visual appearance.  Black opal, generally speaking, is found at Lightning Ridge, but all opals produced at The Ridge are not described as black.  This differs from the system of  pearl classification where, for example, any pearl produced by the Pinctada Margaritifera (black lip) oyster, regardless of body tone, is termed a black pearl.

Grading Opal:

“You can learn diamond grading in an afternoon, learning to grade opal might take twenty-five years.”

Richard T. Liddicoat

In my book, Secrets Of The Gem Trade, The Connoisseur’s Guide…, I devote considerable space to a comprehensive discussion of the grading of opal, thus I will not attempt to cover all bases in this post.  The descriptive system cited above was not in use at the time the book was published (2003).

Saturation levels in opal.  Viewed from left to right the stones show higher levels of saturation (brightness).  Be careful of the last one on the right as it depicts a pattern of large flashes which will appear brighter than the smaller more discrete pinfire play of color in the images to the left.

Figure 2: Saturation levels in opal. Viewed from left to right the stones show higher levels of saturation (brightness). Be careful of the last one on the right as it depicts a pattern of large flashes which will appear brighter than the smaller more discrete pinfire play-of-color in the images to the left. Photo: Cody Opal

Opal is like a light bulb–the brighter, the better.  It is not the given hue, but the brightness or saturation of hue that is the primary criterion of value.  Color, as we know, divides into three components:  hue, saturation and tone.  Hue is color as the term is ordinarily used, e.g. greenish blue, pinkish purple.  Saturation refers to the quantity, or brightness of a given hue.  Figure 2 depicts levels of saturation, although some opal experts prefer the term brilliance. Moving from left to right, the colors become more intense.    As opal types, the first two stones in figure 2 would be classified N1, the third N2 and the fourth probably N3.   N1-N4 are examples of what is normally called black opal.  N6-N7 are called crystal opal and N8-N9 are light opal.

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A black opal exhibiting the rare "peacock's tail" pattern. The opal was cut in a shape that resembled a butterfly's wing. At the risk of mixing metaphors, we designed and created an opal butterfly with a peacock pattern in 18k yellow, rose and white gold. The design rendering is shown as background. Courtesy: R. W. Wise, Goldsmiths. Photo: Jeff Scovil

Patterns:

Pattern is important.  Larger blocks of color are more highly desired than smaller.  Figure 2:  Moving from left to right the color becomes increasingly more saturated. Note also that the stone at the far right is more beautiful because the color is not only more saturated (brighter),  but also because the pattern of  larger chunks of color is both more visible and more pleasing to the eye.  The grading of patterns is unique to opal.  Some, like peacock’s tail, are easily identified because they closely resemble their pattern-name.  There is a hierarchy of rarity associated with pattern that any true opalholic must learn by rote.

Generally speaking, those evocative patterns which are readily identifiable with names like Grass, Chinese Writing and Mackerel Sky are the most desired.  At the very top of the list sits Harlequin, rarest of the rare.  This pattern is named for the ambiguous clown-like figures dressed in suits with large diamond shaped patches which inhabit the paintings of Picasso’s Blue period (see below left).  I have seen only three harlequins in twenty years and only two with a true red component.

Millenium, a 25 carat Harlequin opal sourced by Cody Opal and sold several years ago by R. W. Wise, Goldsmiths  The gem has the the double virtues of large angular blocks of color and a dominent red which is the rarest hue in opal.

Millennium, a 25 carat Harlequin opal sold several years ago by R. W. Wise, Goldsmiths. Millennium is known as a red multicolor because the gem has the the double virtues of large angular blocks of color and a dominant red, which is the rarest hue in opal. Photo: Rudy Weber

Pricing Opal:

Opal prices can vary from a few dollars to hundreds of thousands.  Additional criteria including color and transparency are also key to the valuing equation.  Beauty is, as always, the defining criterion.

In 2008, opal experts Andrew and Damien Cody published a beautiful booklet, The Opal Story, A Guidebook (ISBN: 978-0-9805987).    Aside from some of the most magnificent photographs of some of the finest opals ever to see the light of day, the Codys identify seven value factors in the grading of opal:  type, brilliance, body tone, transparency, pattern, dominant diffracted colors, thickness of color bar and shape. Book CoverThese criteria are consistent with the new Australian system of valuing.  I would advise anyone seeking to sharpen their understanding of opal grading to purchase a copy of this booklet.  The Opal Story Book and DVD is available for $29.95 AUD plus shipping and handling of $6 AUD. Orders can be emailed to opal@codyopal.com . The order should include mailing address and phone number together with credit card details.

New From our Workshop

7071RMSCMa_NW

by Richard W. Wise

© 2009

Crystal Opal

It is always exciting to work with a world class gemstone In this case we began with a 12.15 carat crystal opal.  The stone was found a Lightning Ridge and though this Australian field is known as the source of the he finest black opal, it produces crystal as well.  Crystal is one of the accepted opal type descriptions.  It means that the stone has a transparent rather than a white, gray or black body color (Secrets Of The Gem Trade, p.189).  This stone measures 17 x 14mm with a lovely 9.5mm high dome.    A high dome is desirable because it will concentrate create a sense of movement as the stone moves on the finger and provide a “CinemaScope” side view of the play-of -color.  This tone exhibits a confetti like pattern of sapphire blue, orangy-red and a wonderful foresty, slightly bluish green that partners very well with fine tsavorite garnet.  Despite its many colors, opal is a difficult stone to accent. 3mm round tsavorite garnets

The Setting:

The design is that of a blossom opening to reveal the treasure hidden within.  The soft petal like golden lips serve to present and protect the stone at the same time.   Note the shape of the shank, we provide weight at the back to counterbalance the top-heavy center setting.  Four tsavorites bezel set, one at the base of each of the four split petals.

Sketches were prepared and working closely with our client, we chose 18k royal yellow gold for the setting.  Black opal, particularly those with a vivid display of primary h7071RMSCMc_NWues; red-orange, blue, green, often look their best in 22k.  There are no hard and fast rules to the setting of opal; each gem is individual with a distinct personality that must be carefully catered to.  Design and construction by Michael Corneau.