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.

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.

"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.

"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.

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.

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.

An acceptable situation - HEAT TREATMENT

What do you tell the customer who asks, "Has this gemstone been treated?"
Depending on your answer, that customer will either walk out the door with a bad taste for the jewelry industry or with a greater understanding and appreciation for the beauty of gemstones - and possibly the stone you were showing them.
The improvement of a gemstone's color through a heating process is an everyday occurrence in the gem centers of the world. In Thailand, Sri Lanka, Australia, Brazil - everywhere a gem occurs, there is a treatment to enhance and stabilize the color and bring out the hidden potentials of a stone. Without it, there would be few examples of beautiful gemstones we are all aware of. Conversely, processes such as irradiation and diffusion create color that a stone had no potential to attain and are therefore treatments looked down upon in the trade.
There are several reasons to improve a gemstones color through heating. Light stones may be darkened, dark stones may be lightened. Asterism may be enhance or eliminated.
To accurately answer the opening question, a jeweler can only reply, "probably." Since the process of heating a gem species occurs naturally, man's introduction of heat is merely an extension of nature. In most cases, such treatment is not detectable by a gemologist and therefore cannot be disclosed on a laboratory report. Heating has most assuredly occurred, but the characteristics which identify heating are identical by both man and nature.
The process of heat treatment can only bring out characteristics that a stone already possesses. Pink sapphire will not become gem ruby. The color change in alexandrite will not be appreciably enhanced. Heat treatment has thereby gained acceptance in the jewelry industry. Heat diffusion and other techniques which create a coating to induce color, however, are not acceptable to the trade unless acknowledged and disclosed to the customer.
Heat treatment techniques vary with each gem species as temperature and time expose the important factors. In some cases, solutions are added to the process to facilitate coloration.
Examples of commonly treated gemstones include:

• Aquamarine, out of the ground as green to yellowish-brown beryl, when heated to 400-450 degrees Celsius to produce that familiar light to medium blue "aqua" coloration.
• Reddish brown topaz becomes a salmon-pink or purplish-red.
• Zoisite, which occurs as a muddy greenish-brown is transformed to beautiful highly pleochroic violetish-blue tanzanite.
• Dark blue Australian sapphires are lightened, although a more difficult process, through prolonged heating. Light blue to near-colorless Sri Lanka sapphires gain color through extreme heating.
• Dark green tourmaline is reduced in tone to a pleasing medium-green.

Heat treatment is not without its pitfalls. Sapphire is most often heated to just below its melting point, making the process all the more difficult. Much money has been lost through "overbaking" to a point of ruining a stone.
If you're still stuck for an answer to a question "Has this gemstone been treated?" liken the process cookies - the dough's OK, but wait til they come out of the oven!