Professional Jeweler Archive: Nesting Spot for the Heart

January 2004

Gemstones & Pearls/Gemology


Nesting Spot for the Heart

You can determine a lot by looking at sapphires up close. Use the magnificent scenery you encounter to sell the gems

Sapphires often display spectacular inclusions when viewed through a binocular microscope. Aside from being pretty – and salable – these inclusion landscapes can contain evidence of the sapphire’s country of origin, whether it was treated and whether it’s natural or conceived in a laboratory. Even non-gemologists can learn the basics of looking at sapphire inclusions. Here’s how.

Diving In

Find out whether your store has a binocular microscope (one with two oculars for your two eyes). This allows stereoscopic vision, meaning you see your subject three-dimensionally. It also allows you to determine the depth at which the inclusions lie and their relative size.

You’ll also need tweezers to secure your loose gem or jewel so it remains still and so your hands are free to fine-tune the focus and zoom controls. Your hands also should be free to change the viewing angle by rotating the tweezers holding the gems. Do this until you spot a characteristic requiring particular attention. Then refocus and play with lights to reveal additional hidden secrets.

Lighting

Lighting is critical in determining how you or your customers see the gem’s internal scenery. Most gemological microscopes are fitted with darkfield illumination wells. The tweezers containing the gem are positioned above the light well, allowing diffused side lighting all around the gem.

At the bottom of the well, a lever allows you to see transmitted lighting or a black background. The black background constitutes the darkfield illumination feature of your microscope. Gemologists often use it because inclusions are evenly lighted from the sides and stand out in high relief against the background. Some gemologists use separate light sources, such as fiber optic illumination, to increase the contrast between the inclusions and the body of the gem.

One Typical Gem

In the pink sapphire pictured on page 42, you can see a concentration (or nest) of fine rutile needles, proving it is natural in origin and untreated (rutile “silk” melts, or partially melts, during the heating process associated with treatments). The needles are crisp and oriented in three directions. There are larger included crystals, probably composed of calcite or dolomite, which are typical of a gem with a Burmese pedigree. One of them is shaped like a heart: a heart at the heart of the gem. Not only is the gem salable because of its apparent natural, untreated state. The uniqueness of its inclusion – which you can confidently tell your customer is to be found nowhere else on earth – renders it a collector’s gem par excellence.

– by Robert Weldon, G.G.

A nest of glistening rutile needles accompanies the heart-shaped calcite inclusion shown under. 45X magnification. This inclusion is from the sapphire shown at left. Photo by Robert Weldon.
3.08-ct. natural pink sapphire is from Mogok, Myanmar (formerly Burma). Bear Essentials, Jefferson City, MO; (800) 753-4367. Photo by Robert Weldon.

Copyright © 2004 by Bond Communications