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.