Rapaport Magazine
Colored Gemstone

Tucson’s Top Five

May Colored Gemstone

By Robert Genis
RAPAPORT... The world’s colored gemstone dealers converge on Tucson. Here are some of the best finds from recent shows.

You can buy a gem of almost any price at the Tucson Gem Shows, from $5 per carat to million-dollar gemstones. Not only does Tucson have colored gemstones, but also colored diamonds. Although white diamonds are unusual in Tucson, a new colored diamond section premiered at the recent American Gem Trade Association (AGTA) Show.

The following five showstoppers were not necessarily the most expensive stones, although two of them break the million-dollar barrier, but they are all unique and precious and outstanding in their own right.


At the Centurion at La Paloma, John Buechner, John Buechner, Inc., Chicago, Illinois, showed a 1.62-carat, fancy intense, bluish-green oval diamond. The stone, which looks very similar to a Brazilian electric Paraiba tourmaline, has a Gemological Institute of America (GIA) Grading Report. The diamond, whose clarity is VS, has even color distribution and no fluorescence. It is mounted in platinum. The side stones are intense purplish pinks with a total weight of two-thirds of a carat.

The stone was found by Bob Klose and Steve Lennox of Images Jewelers, Elkhart, Indiana, for a private collector. It sold for $1.2 million right after the show. “I have sold straight reds and greens, but this was a very, very special stone,” comments Buechner.


A 325.13-carat gem tsavorite was displayed by Michael Couch, Michael Couch and Associates, West Des Moines, Iowa, at the AGTA Show. Green garnet was discovered in 1968 in the Tsavo National Game Park in Kenya by miners who thought they had found a new source for demantoid garnet. Today, there are small mines operating in Kenya and Tanzania. High-quality tsavorite is rarer than emerald, cleaner and more brilliant, and is not altered with oil or heat. As a general rule, it is found in small sizes. A 3-carat gem tsavorite is rare, although occasionally, a stone up to 10 to 20 carats is seen.
According to Couch, an exceptional 925-carat tsavorite was recently found in the Karo area in Block D at Merelani, Tanzania, at a depth of 450 feet. “The depth where this stone was found is really deep in a third world country. You have to remember the miners have no ventilation and it is extremely dangerous to be at these levels,” says Couch. The rough is believed to be the largest ever discovered. From the rough, a 62 carat, a 120 carat, a 307 carat and the 325.13 were cut. Only the 120 and the 325 are clean.

The 325.13-carat stone, which has GemResearch Swisslab (GRS) and AGTA Grading Reports, is a vivid gem green color and clean. It measures 42.11 by 36.46 by 28.34 millimeters (mm). The issue with the stone is the proportions: The culet is cut slightly off center and a small window is evident. The price? A cool $2.2 million.


It is no secret that the amount of goods coming from Burma has dwindled and that the new stones are considerably higher in price than in the past. Thanks to the internet, where word travels at light speed even to third world countries when a large stone sells at auction, the Burmese dealers know about it also. This causes them to probably overvalue the goods they have.

Jack Abraham, Precious Gem Resources, New York, New York, had a 37.89-carat, oval Burma sapphire at the AGTA show. The gem, which has an American Gemological Laboratory (AGL) Grading Report, has a rare 75 percent blue primary color, a 2.5/85 color/tone, and an excellent Total Quality Integration (TQIR). Its measurements are 18.85 by 17.16 by 13.22 mm; the depth is 77 percent. The stone is Moderately Included, but the inclusions are difficult to see because the stone is so saturated. The sapphire has good proportions and finish and high brilliancy. It is not heated and is not clarity enhanced. It is mounted with diamonds.


Recently discovered in Mozambique, Africa, a brand-new tourmaline rivals the colors of tourmaline from Paraiba, Brazil. The collector market has been in search of a new product since the Brazilian Paraiba has dwindled in size and availability. Although not as vivid as the original Brazilian material, the heated Mozambique colors are close.

The largest new Mozambique Tourmaline was a 76.91-carat square antique, modified brilliant. The stone was available at the AGTA Show from Barker and Company, Scottsdale, Arizona. The gem has an AGL Grading Report. The measurements are 25.31 by 24.89 by 18.39 mm. It is green blue in color. According to Barker, “the stone is unusual because it faces up green and upside down, it is blue.” Although not as fine as others seen at the show, the color would be the next tier down from the best. The stone is flawless, with superior cutting and high brilliancy. It was subjected to low/moderate heat. The price is $6,000 per carat or $461,460.


Spinel is considered a gem dealers’ stone because they tend to covet and desire the gemstone more than the public. Spinel prices have been increasing dramatically lately in Burma and old spinels are being taken back to Burma to be resold. Any gem red spinel from Burma over 3 carats has always been rare. You can count on your fingers the number of Burma gem red spinels over 10 carats, making this gem oval 12.86-carat, red/orange Burma spinel at the show noteworthy.

The gem has an AGL Grading Report. The stone, with a color grade of 3.5/70, is vivid red with a light tone. It is Lightly Included. Its measurements are 14.64 by 12.74 by 9.13 mm and its depth is 71.6 percent. The spinel has good cutting and finish and almost the brilliancy of a diamond. It has not been enhanced or clarity treated. It is owned by a private collector who simply wanted to display the stone.

Article from the Rapaport Magazine - May 2007. To subscribe click here.

Comment Comment Email Email Print Print Facebook Facebook Twitter Twitter Share Share
Comments: (0)  Add comment Add Comment
Arrange Comments Last to First