Photonics Weeds out the Impostor Jewels

Jennifer L. Morey

How many times have you opened the mailbox to read, "Congratulations! If you have the winning number, you will receive a valuable diamond pendant"? Your excitement builds when you see that your number matches the winning number, only to be let down when you read in the fine print that the "valuable" pendant is worth only $3.97.
Common sense tells us that a free gemstone is not all it's cracked up to be. But when you're slapping down several thousand dollars at the jewelry store, how can you be sure you're getting the real thing and not just the latest laboratory creation?
Jewelers commonly rely on equipment such as binocular microscopes and spectroscopes to distinguish even the most well-disguised impostor from a bona fide original. Ironically, synthetic gem materials can be easy to spot because they typically don't possess any of the flaws characteristic of natural stones.
James Shigley, director of research at the Gemological Institute of America, uses visible spectroscopy to examine the color in stones such as rubies, or IR spectroscopy to look at materials, such as plastic, that are used to treat gemstones and that exhibit a characteristic IR spectrum.
Making and selling synthetic gem materials is not a crime. Many are labeled correctly when they are first sold, but this information often can get lost as stones change hands. The institute has no regulatory role in the industry, but if you try to misrepresent a fake stone or pearl as the real thing, watch out! Photonics is watching.