Finding the Fakes

     IF A DIAMOND SCRATCHES GLASS, YOU KNOW ITS A REAL DIAMOND. BUT NOT
EVERY GEM IS SO EASY TO DISTINGUISH FROM THE FAKES.  TURQUOISE FOR EXAMPLE, CAN
BE FAKED SO WELL WITH  BLUE PLASTIC THAT EVEN AN EXPERT CAN HAVE A HARD TIME
DETECTING IT.  UNTIL RECENTLY THERE WAS ONLY ONE WAY TO TELL FAKE TURQUOISE
FROM THE REAL THING, SAYS CHEMIST DON BURNS AT LOS ALAMOS NATIONAL LABS--BUT
YOU HAD TO DESTROY THE JEWELRY IN ORDER TO DO IT. 

     Burns: "I saw a TV program . . .and someone was explaining how you could
determine if turqouise was real or not by heating it in a crucible, and when I saw this
crucible with a torch under it, it occurred to me that there has to be a better way to do
it." 

     THE BETTER WAY TO DO IT IS TO USE A STANDARD SCIENTIFIC TECHNIQUE CALLED
SPECTROSCOPY WHICH HE'S USED FOR YEARS TO DISTINGUISH BETWEEN DIFFERENT KINDS
OF PLASTICS.  BY BOUNCING LIGHT WAVES--IN THIS CASE NEAR INFRARED WAVES--OFF OF
AN OBJECT, YOU CAN FIGURE OUT WHAT ITS MADE OF. 

     Burns: "Our mental picture is often that if when light hist the surface of something it
gets scattered in all directions, and comes right back to us. Actually, the light penetrates
some distance below the surface and it interacts with the molecular strucutre and its
changd by that interaction, so the light that comes back is a little bit different. . . and we
can regard that as sort of a fingerprint." 
     
     BURNS HAS AN EXTENSIVE DATABASE OF WHAT THE FINGERPRINTS BOUNCED OFF
OF PLASTIC LOOK LIKE AND THEY LOOK VERY DIFFERENT FROM THOSE BOUNCED OFF
TURQUOISE.  

     Burns: "The spectrum will tell us immediately if this is made of plastic and is not the
real McCoy."

     EASY ENOUGH FOR TURQUOISE, NOW BURNS HOPES TO TACKLE OTHER FAKES,
SUCH AS CORAL, AND EVEN DOLLAR BILLS TO GIVE ALL COUNTERFEITERS A RUN FOR THEIR
MONEY.