In frustration, I whispered back to Peridot, “That’s what I’m trying to do. What am I missing?” We were seated in Florence for dinner with Davies, Richard Leyland, and Renaldo Rossi, across the street from La statue de la Justice.
Leyland handed Peridot his parcel, and with a flick of his fingers Peridot opened the paper and that lovely yellowish Green gem appeared. Identical to the one I was holding. In his best professor’s voice he began. “Gentleman, it appears we’ve had a slight mixup here.”
“How can you be sure?” asked our art collector, Leyland.
“Bontemps, what is the unique property that gemologists measure to determine a stones identity?”
“It’s refractive index, of course.” I said.”
“Correct, and what is the refractive index of Peridot?”
“Peridot has a refractive index of 1.654 to 1.690. It exhibits a high birefringence, and a greasy luster.”
Peridot raised his index finger. “We need to be more specific my boy. Refractive index is the ratio of the speed of light in a gem compared to the speed of light in air.” said Peridot. Yes, birefringence tells you the stone is doubly-refractive. The light is split into two beams as it enters the gem. As a result you will see doubled images within the stone.
“Bontemps, the stone you have, what would you say its luster appears to be?”
“Greasy,” I said with confidence.
“Precisely!” remarked Peridot. Now let’s compare Synthetic Spinel. What is it’s R.I.?”
“Ah I see where you’re going,” said Bontemps. Synthetic Spinel is singly refractive it’s R.I. measures 1.728. There are no doubled images.
“Correct again.” Said Peridot. “That is an important clue. The higher R.I. lends itself to a higher luster, a vitreous, glass-like appearance.
From his vest coat pocket Peridot pulled a tiny tube about the size of Chapstick tube and handed it to me. “Adamas, with your penlight would you check your stone for a spectrum? You should see three strong bands in the blue/green area of the spectrum.”
Carefully cupping my hands around the gem to limit the ambient light, I passed a beam of light through my gemstone and sure enough, three strong absorption bands appeared. “This is definitely the Peridot. The absorption spectrum proves that.”
Davies spoke. “Yes, the stone destined for the art exhibit is another of my exquisite creations. It is difficult to create synthetic spinel in Peridot green, but not impossible. During my meeting with Professor Rossi, at the Uffizi, we examined the Peridot from the Natural History Museum in Los Angeles together. I presented this marvelous creation to Professor Rossi for examination. He immediately identified it as a fine example of Synthetic Spinel. My compliments again to you professor, and to you cousin, it appears you have mentored your students well.”
“We agreed, in this particular case,” said Rossi that Mr. Davies would present the synthetic spinel to Leyland for display in his art exhibition with a placard that the Uffizi Gallery had the original on display for a limited engagement. “Mr. Leyland, any objections?”
“No, not at all,” said Leyland quietly. “Is the synthetic spinel replica for sale?”
Davies chimed in, “Allow me to point out the the attention to detail.”
“Later - we will talk business later. We have many other beautiful creations that you may find enticing for your gallery exhibits.”
“Excellent,” said Peridot. There’s one final detail to clarify before we adjourn. This so-called elephant in the room. The stigma of synthetics. It appears that a formal education in Gemology places an unconscious bias on natural vs. synthetic gems. As my cousin has demonstrated, there will always be a market for exquisite creations from a laboratory. With full disclosure I say make it so.”
With that statement Peridot held up his glass of wine and proclaimed a toast. “Gentleman, the science of deduction, like any skill, must be practiced daily to be perfected. This trip to Florence has been an absolute pleasure for me and my young protege Adamas Bontemps, thank you!”
After sipping his wine Professor Rossi raised his eyebrows and said, “My friend, before you leave Florence you must tell me more about this impregnated flexible diamond-thin film polymer on your shoes.”
. . . To be continued.
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