The days of the one line generic jewelry appraisal are numbered. The insurance industry is becoming more involved in the type of appraisal their clients obtain and sending them to independent laboratories for complete and accurate gemological descriptions - like the ones NGL has offered for over a decade.
In addition, diamonds individually valued at over $10,000 often require a diagram of their internal characteristics. This service is always available through NGL and although we recommend a loose diamond for such inspection, mounted diamonds can be plotted as well.
The most significant changes in the appraisal business are going to be coming from new legislation, however. In both the US Congress and Washington state legislature, bills to regulate the appraisal industry are being reviews and will be seeing action soon. First affected will be the real estate business, long a target for congressional scrutiny, but next will be personal property appraisers, such as those of fine jewelry. We at NGL welcome this intervention, but only hope sufficient requirements and limited "grandfathering" for appraisers is also enacted.
Sunday, October 1, 1989
Monday, October 1, 1984
Laser-drilled diamonds require disclosure
Laser-drilled diamonds are not new to the industry, but many jewelers are concerned when labs add the statement "diamond has been laser-drilled" to the bottom of their appraisal.
Since some jewelers are not aware of what is involved in this technology and fear that their customers will be alarmed at such information, they would rather not have to deal with the subject. Aside from FTC rulings requiring disclosure, laser-drilling of a diamond should not be side-stepped.
The lasering process simply improves the "look" of a stone by lightening a dark inclusion. Through a microscopic drill hole, acid may be injected into the diamond toward an unsightly inclusion - those most customers refer to as "carbon spots". In contact with the acid, the inclusion is bleached and becomes less visible to the observer.
It must be noted, however, that while drilling may improve a diamond's appearance, it cannot improve its clarity grade.
Since some jewelers are not aware of what is involved in this technology and fear that their customers will be alarmed at such information, they would rather not have to deal with the subject. Aside from FTC rulings requiring disclosure, laser-drilling of a diamond should not be side-stepped.
The lasering process simply improves the "look" of a stone by lightening a dark inclusion. Through a microscopic drill hole, acid may be injected into the diamond toward an unsightly inclusion - those most customers refer to as "carbon spots". In contact with the acid, the inclusion is bleached and becomes less visible to the observer.
It must be noted, however, that while drilling may improve a diamond's appearance, it cannot improve its clarity grade.
Surface-filled corundum emerging from Thai "kitchens"
More and more rubies are appearing in Thailand with their surfaces "repaired". The process, which fuses a glass substance to the corundum, fills cavities that would have been left after cutting. Since removing such blemishes through cutting would mean a lighter and less valuable finished stone, the technique can mean the difference of profit and loss to this cottage industry.
Microscopic examination easily identifies filled cavities. Immersion in methylene iodide will show a high relief of the filled area and if a refractive index can be taken of the spot in question, a glass reading will be observed. In addition, gas bubbles may very well be present in the filled area.
Microscopic examination easily identifies filled cavities. Immersion in methylene iodide will show a high relief of the filled area and if a refractive index can be taken of the spot in question, a glass reading will be observed. In addition, gas bubbles may very well be present in the filled area.
Thursday, August 30, 1984
"New process" enhances lower priced cultured pearls
Demand for lower prices cultured pearls has prompted a new process from Japan which adds a rosé overtone to otherwise white, thin nacred pearls.
Since 80% to 90% of Japan's pearls are exported to this country and their demand has been increasing, especially in the lower end goods, the Japanese began experimenting with a dye process that imparts a color more attractive to the US market.
Although the culturing time is still short - eight to twelve months, in most cases - the dye adds a pleasing color while keeping the price low.
Detection of the dye is generally not a problem, as concentrations usually appear around the drill hole or near surface blemishes.
This procedure has been in use for about one year and is expected to show up more heavily in this year's Christmas season.
Since 80% to 90% of Japan's pearls are exported to this country and their demand has been increasing, especially in the lower end goods, the Japanese began experimenting with a dye process that imparts a color more attractive to the US market.
Although the culturing time is still short - eight to twelve months, in most cases - the dye adds a pleasing color while keeping the price low.
Detection of the dye is generally not a problem, as concentrations usually appear around the drill hole or near surface blemishes.
This procedure has been in use for about one year and is expected to show up more heavily in this year's Christmas season.
Sunday, April 1, 1984
"You may have already won..."
It's contest time for many of the national sweepstakes companies and once again, NGL s deluged with calls concerning the "Black Star of India." From our examinations, this often-awarded runner up prize is a natural black star diopside, valued at around one dollar.
Some of the other "prizes" we've seen include the "Tigris Emerald", a natural but excessively included emerald of negligible value and a natural ruby of similar description.
Some of the other "prizes" we've seen include the "Tigris Emerald", a natural but excessively included emerald of negligible value and a natural ruby of similar description.
Cat's Eye Synthesized
Following three years of development, Sumitomo Cement Co. of Tokyo has filed patents for what is thought to be the first synthetic cat's-eye chrysoberyl.
A beryllium oxide base is dissolved under strictly controlled conditions with a "brilliance-producing additive" at 2000 degrees Celsius to produce a single crystal.
According to a leading Japanese gemologist, the product duplicates the properties of the finest grade of natural cat's eye chrysoberyl.
A beryllium oxide base is dissolved under strictly controlled conditions with a "brilliance-producing additive" at 2000 degrees Celsius to produce a single crystal.
According to a leading Japanese gemologist, the product duplicates the properties of the finest grade of natural cat's eye chrysoberyl.
Sunday, January 1, 1984
Coated Diamonds Appear in New York
A not so easily detected coating for diamonds has made its appearance in New York, reports National Jeweler (December '83). A silicon and plastic composite is "sputtered" onto the diamond using plasma physics, leaving no brush marks and thereby making detection difficult without a microscope.
At present, very few stones have been examined, but alert has gone out to be aware of the process. Not only is the coating used for creating a "fancy" color for diamonds, but also to improve apparent color in the G to L range. Treatment for fancies is generally a heavier coating and is applied to the entire pavilion of a low color stone. For improvement of two or more grades, a coating with a slightly bluish cast is applied to the girdle.
Since color grading is generally not done with a microscope, this treatment may easily go unnoticed. The silicon component adds color while the plastic increases durability requiring an acid and acetone combination for the coating's removal.
At present, very few stones have been examined, but alert has gone out to be aware of the process. Not only is the coating used for creating a "fancy" color for diamonds, but also to improve apparent color in the G to L range. Treatment for fancies is generally a heavier coating and is applied to the entire pavilion of a low color stone. For improvement of two or more grades, a coating with a slightly bluish cast is applied to the girdle.
Since color grading is generally not done with a microscope, this treatment may easily go unnoticed. The silicon component adds color while the plastic increases durability requiring an acid and acetone combination for the coating's removal.
