Rare Faceted Blue Tanzanite Up For Auction

May 13th, 2010 iregress Posted in Faceting, Gemstones, jewelry No Comments »

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 Rare Faceted Blue Tanzanite Up For AuctionIf you have an estimated $18,000 - $25,000 laying around and you are looking for a large faceted, royal blue Tanzanite then you're in luck!

The Bonhams New York Auction house is having a Natural History auction on May 27,2010.

Up for grabs are a number of highly sought after specimens of amber, fossils, meteorites, exotic gemstone jewelry and more.

One of the highlights from the gemstone lapidary arts area is this large faceted Blue Tanzanite gemstones.  It is a cushion-cut stone that comes in at an eye popping 71.98 carats!.

Tanzanite has become a highly sought after gemstone in the United States ever since trade embargos with the Tanzanian government has made the acquisition of Tanzanite more and more difficult to obtain.

The blue Tanzanite stone is just one of numerous faceted gemstones that will be up for auction in this fund raising event.  Included in the auction will be a black opal diamond pendent in the shape of a butterfly...it's a stunning 18.27 carat black opal specimen from Lightening Ridge Australia.  It is anticipated that the stone will go for as much as  $40,000!

These are just a couple of the items available.  This will be a once a lifetime opportunity to obtain some of the worlds most beautiful gemstones, and the finest output of the lapidary arts.

120710638684 0 Rare Faceted Blue Tanzanite Up For Auction
405 CT FINE NATURAL CRYSTAL GREEN TOURMALINE RARE GEMSTONE THAIROCKSHOP
pp Rare Faceted Blue Tanzanite Up For Auction   US $11.99
120710638685 0 Rare Faceted Blue Tanzanite Up For Auction
3⅞ CT FINE NATURAL CRYSTAL GREEN TOURMALINE RARE GEMSTONE THAIROCKSHOP
pp Rare Faceted Blue Tanzanite Up For Auction   US $11.99
120710638692 0 Rare Faceted Blue Tanzanite Up For Auction
4¼CT FINE NATURAL CRYSTAL GREEN TOURMALINE RARE GEMSTONE THAIROCKSHOP
pp Rare Faceted Blue Tanzanite Up For Auction   US $9.99
110598212173 0 Rare Faceted Blue Tanzanite Up For Auction
Ruby in Zoisite Cabachon 48cts VERY RARE Gemstone NEW
pp Rare Faceted Blue Tanzanite Up For Auction   US $1,056.00
120670807209 0 Rare Faceted Blue Tanzanite Up For Auction
581 Ct NATURAL SMOKY QUARTZ FACET CUT RARE GEMSTONE
pp Rare Faceted Blue Tanzanite Up For Auction   US $12.99
260720581572 0 Rare Faceted Blue Tanzanite Up For Auction
207 Ct NATURAL SMOKY QUARTZ FACET CUT RARE GEMSTONE
pp Rare Faceted Blue Tanzanite Up For Auction   US $14.99
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Read more about this exciting auction at Bonhams New York, Technorati Tags: lapidary arts, tanzanite, tanzanite gemstone, Bonhams New York

 Rare Faceted Blue Tanzanite Up For Auction
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Why Some Gemstones are Cut as Cabochons

December 1st, 2009 iregress Posted in Faceting No Comments »

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Author: GemSelect
In the gemstone world, a cabochon is a stone that is cut with a highly polished rounded or convex top with no faceting, with a flat or slightly domed base. A cabochon may be cut in any shape, though oval is by far the most common. The term comes from the French caboche, meaning knob or small dome. Certain stones are almost always cut "en cabochon," including opal, turquoise, onyx, moonstone, and star sapphire. In the gemstone world you will often hear the term cabochon shortened to "cab."

Technically, cabochons are not really "cut." Rather they are shaped and then polished. It is thus a much simpler task to produce a cabochon than it is to cut a faceted gem with many faces. Before the art of faceting was developed, all gemstones were produced as cabochons, though some were intricately carved as well.

Faceted gemstones
made their appearance in European jewelry during the late 13th and early 14th centuries. With the advent of the horizontally turning cutting-wheel in the late 1400's came the possibility of designing and repeating elaborately conceived geometric faceting schemes, thereby controlling and enhancing the light coming from within the stone.

The fascination with geometry and reflected light during the Renaissance accelerated the development of a sophisticated lapidary art. Starting with the Renaissance gem-cutting trade in Bruges, to Venice, Florence and eventually the whole of Europe, the management of light became the central theme in gem cutting.

390386769127 0 Why Some Gemstones are Cut as Cabochons
Bracelet and Earrings Set Silvertone and Blue Cabachons Wonderful Deep Blue
pp Why Some Gemstones are Cut as Cabochons   US $29.99
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12 sq lush BONE ULTRASUEDE® SOFT CABACHON CRAFTS
pp Why Some Gemstones are Cut as Cabochons   US $5.55
200585959700 0 Why Some Gemstones are Cut as Cabochons
SENSATIONAL CABACHON PERIDOT GOLD BRACELET
pp Why Some Gemstones are Cut as Cabochons   US $624.10
310331121998 0 Why Some Gemstones are Cut as Cabochons
Vintage Lion Head Red Cabachon Clip Back Earrings
pp Why Some Gemstones are Cut as Cabochons   US $13.99
180810210874 0 Why Some Gemstones are Cut as Cabochons
VINTAGE BEAUTIFUL CABACHON STONE SILVERPLATE BRACELET EXCELLENT
pp Why Some Gemstones are Cut as Cabochons   US $9.99
400268423569 0 Why Some Gemstones are Cut as Cabochons
Vintage Clay Glass Cabachon Pin Brooch CAT RESCUE
   US $49.99
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Once the technology and skill was available to facet gemstones, why were cabochons still produced? The question is an interesting one because different gems are cut as cabs for different reasons. In many cases it is because the gem has special properties that are displayed only when it is cut as a cabochon. Examples are gems that display asterism (the star effect) or chatoyancy (the cat's eye effect) or iridescence (e.g., opal) or adularescence (e.g., moonstone).

Most gems that are opaque rather than transparent are cut as cabochons rather than faceted. You will also see lower grade material in gemstones such as sapphire, ruby and garnet cut as cabs. If the gem material has very good color but is not sufficiently transparent or clean to be faceted, it can still be shaped and polished to be a very attractive cabochon. It is also common to cut softer stones as cabs, since gems with a hardness less than 7 (on the Mohs scale) can easily be scratched by the quartz in dust and grit. Minute scratches show much less on a cabochon than on a faceted stone.

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ROTTLER DIAMOND LAP FITS ALL ROTTLER BORING BARS
pp Why Some Gemstones are Cut as Cabochons   US $99.00
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Diamond Lap Flat 6 Lapidary Diamond coated 6 Lapping
pp Why Some Gemstones are Cut as Cabochons   US $20.19
290549970393 0 Why Some Gemstones are Cut as Cabochons
6 Crystalite The Standard Diamond Lap 100 grit
pp Why Some Gemstones are Cut as Cabochons   US $102.00
300632989593 0 Why Some Gemstones are Cut as Cabochons
6 Crystalite Plated Flexible Diamond Lap 70 mesh
pp Why Some Gemstones are Cut as Cabochons   US $54.00
300632990326 0 Why Some Gemstones are Cut as Cabochons
6 Crystalite Plated Flexible Diamond Lap 600 mesh
pp Why Some Gemstones are Cut as Cabochons   US $38.00
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8 Crystalite Plated Flexible Diamond Lap 600 mesh
pp Why Some Gemstones are Cut as Cabochons   US $50.00
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GemSelect is a leading online dealer in fine gemstones, specializing in sapphire, spinel, tourmaline, topaz and zircon. Cabochon Gemstones

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