By Emily Stegman

Alan Hodgkinson, F.G.A., D.G.A., doesn't have to rely on a spectroscope, refractometer or microscope each time he identifies a gemstone. The moon, a candle or the corner street lamp will do just fine.

His gemstone-to-eye method, which he has coined "Visual Optics," involves direct observation of the optical properties of a faceted gemstone. It's done by holding a stone close to the eye and examining it through a distinctive light source at any distance.

"Let me make myself clear here," he said. "We can't do without our refractometers and spectroscopes and microscopes and loupes, but what do you do if you don't have them available to you? That's when Visual Optics can step in quite usefully."

Hodgkinson said that with experience, gemologists can use Visual Optics to help identify a gemstone when the refraction, dichroisms or birefringence/dispersion ratio of the resulting light patterns are considered.

"Now, that doesn't solve the question of natural or synthetic – that calls for the loupe. But I'm trying to get across to you what a lot of fun you can have even if you haven't got a laboratory ticking underneath you," he said.

Hodgkinson began his career in gemology in 1957 and has since developed the highly acclaimed two-day Practical Gem Identification Course in the United Kingdom and was the first recipient of the Antonio Bonanno International Award from the Accredited Gemmological Association in 2000. He has also been published in several trade journals, written Hodgkinson's Visual Optics and is working on a new book, Gem Testing Techniques, due out later this year that expands on his gemstone identification methods.

Hodgkinson's extensive gemological experience has brought him to the United States from his native Scotland several times for lectures and presentations over the past 16 years. The San Diego chapters of GIA's Alumni Association and the Women's Jewelry Association welcomed him in February for a presentation titled "Some Gemmological Tricks and Treats."

Hodgkinson showed attendees the validity of his tricks firsthand.

He identified a diamond, synthetic moissanite and zircon stone by viewing each through a pinhole in a piece of paper, shining a small flashlight on the stone and analyzing the resulting light patterns. He said a candle set 20 yards away, however, would have been his first choice.

"If you were to put a newspaper this close to your face, you wouldn't be able to read the words because your eyes simply can't focus on them that close. It's the same thing here – it's not the stone I'm seeing, but the light patterns it creates," he said.

One of Hodgkinson's favorite stories where Visual Optics came to his rescue involves a double-stranded ruby necklace a friend's wife purchased in Australia. She wanted to know its true value and Hodgkinson only had an hour before he had to catch a flight.

"A quick look at the necklace told me it was predominately made of red spinel, but I had to be sure. My friend, being a lawyer, wanted the analysis in writing so his wife could get her money back," he said. "If there were even one or two rubies in the strands, it would get messy and of course my reputation would be involved."

The beads were a mere one millimeter in size and strung on a white thread, meaning they were too small for a refractometer and the thread would have created strange birefringence in a polariscope.

"I was so desperate that I dragged the strand across the nose of a handheld fiber optic light," he said. "As I dragged it across, the fluorescent line for spinel stayed coherent the whole time until, all of the sudden, it picked up two rubies."

Hodgkinson made this discovery within seconds and ended up finding several other scattered rubies.

"As I was leaving to catch my plane, I told them they owed me 50 pence a stone," he said. "There were over 600 stones on that double strand! It must've taken a minute or two and it was some of the best money I ever earned."

"And that's Visual Optics – it's such a lot of fun!"

The Speaker's Bureau was established in 1999 to help GIA Alumni chapters plan successful educational meetings. Each chapter receives a reference manual that contains a list of available speakers with his or her area of expertise, presentation description and travel requirements.

"I refer to the Speaker's Bureau manual when someone suggests a speaker I haven't heard or when I'm brainstorming with the local officers about a lineup of speakers for the next year," Starla Turner, co-president of the California Golden-Gate Chapter, said. "It's a fantastic resource when looking for people in the immediate area that you didn't know were willing to speak, or for those important names on the other side of the country that you only read about."

The manual is updated periodically and will be completely revised in 2006 to ensure that alumni chapters have access to speakers who discuss the most up-to-date topics in the industry, said Alumni Relations Manager Rose McKenna. A list of participating speakers will be added to the Institute's Web site when the updates are complete.

"Our alumni chapters provide continuing education and the latest information to graduates about this dynamic industry," she said. "The Speaker's Bureau is a way for chapter officers, who have busy lives of their own, to have an easily accessible resource to help them organize meetings that will benefit their chapter members."