Gemscentric

Written by Julian Robov


Fifty Four


At noon the next day, Rudy and James were back at the Don Muang International Airport, waiting at the arrival lounge. Two hours later, Ms Jambo was escorted to a waiting limo. They were headed to Paratip Court, located in a leafy lane off Bangkok’s central business district. James was totally absorbed by her well-proportioned and symmetrical body, especially her Christian Lacroix coat dress, and magnetic but beautiful look. A NUCLEAR BOMB.

Manuel Pinpointiff, a consultant-gemologist arrived for the rehearsal with a portable lab, sample stones and other gadgets. First, using slides he explained the different qualities of natural blue sapphires from Kashmir, Burma, Cambodia, Thailand, Laos, Sri Lanka, Nigeria, Kenya, Tanzania, Madagascar, Malawi, the United States and Australia. Without a loupe, he began to show samples of natural blue sapphires explaining the correct but flexible distance required to view their colors under a light source–fluorescent, incandescent and skylight. They all looked different: blue, violetish blue, greenish blue, milky blue, and inky blue. Since the sample stones were oval and cushion, he described how to estimate the saturation (intensity, vividness), tone (relative lightness or darkness, gray) in different positions. Blue sapphires happened to look good under fluorescent light while washed out in incandescent light. The focus was on brilliance flashes—its life, its beauty. She was sharp, observant, and asked a lot of questions, as they rehearsed to simulate as natural as possible—like an experienced buyer. Then he proceeded to explain, how to estimate brilliance by rocking the stone in different angles, in order to qualify whether it was poor, fair, good, very good or excellent. The importance of extinction (light leakage due to deep cut), windows (light leakage due to shallow cut) and color zoning was displayed in three dimension using glass and a light box.

James and Rudy watched patiently, as she practiced, sipping grape juice.
Then, Manuel explained about clarity—clean, lightly included, moderately included, visibly included, and heavily included. He had samples to show, and taught her how to use a loupe and grade the clarity. It was difficult and subjective. But at least she got an idea, as to why they were graded differently taking into account the size, color, location, number, and type of inclusions. With the help of slides and a microscope she was able to recognize liquid fingerprints, crystals, needle-like inclusions, iron stains, two-phase and color zoning. The importance of good proportions, symmetry, and finish, which described a way of estimating cut was briefed with sample stones. At least in Southeast Asia, most of the blue sapphires were cut for weight, due to the size and shape of rough crystals—the obvious shapes being oval and cushions with mixed cut. In the end, the whole exercise helped her to get a feel of how natural blue sapphires looked, and since her job was to enact a similar expertise, she rehearsed repeatedly making sure she understood the procedures. She was enjoying the experience.

After a thirty minute break, he proceeded to explain enhancements—such as heat treatment, surface diffusion-treatment, dyeing, assembling, surface repairing and irradiation. Identifying heat-treated blue sapphires from their untreated counterpart was difficult. The only clue to separate them was from inclusions. The liquid patterns, exploded crystals, and the needles (silk) appearance looked quite different, and it wasn’t easy to recognize those differences in a short time, but at least with the help of slides and sample stones she was able to recognize the difference with the help of a microscope. With a loupe, the experience was different and difficult. Lighting also made it less precise.

Their focus now turned to surface diffusion-treatment. Under visual observation, the surface diffusion-treated blue sapphires looked deceptive. They were natural stones, and without the deposition of that magic blue layer, the stones would have looked different. The only way to identify them was to observe the samples under a microscope with an immersion cell. The magic methylene-iodide liquid made the identification easier. She was advised to look for color concentrations at the facet junctions and girdle plane. It was very characteristic of surface diffusion-treated blue sapphires.

The color patches or banding looked different in a natural blue sapphire, and they were too obvious. She then tried to view them with a loupe without immersion technique. It was difficult. With rubbing alcohol she saw the tell-tale signs, but methylene-iodide was the best. And this was the kind of stone Seri was going to show her so she repeated several times observing the samples from all direction. It was an experience.

Dyeing blue sapphires was quite unusual compared to rubies, but identifying those stones wasn’t that difficult. Methylene-iodide or sometimes even a rubbing alcohol was adequate to detect them.

Assembling of blue sapphires too were common. Manuel showed her two sample stones. They all looked blue face-up (table-up). The first sample was a doublet; crown—natural colorless or light green sapphire; pavilion—synthetic flame-fusion blue sapphire. The second sample was a doublet too; crown—natural; pavilion—natural. She had no difficulty detecting with a loupe. The girdle plane looked very thin and sharp.

Surface repair normally consisted of filling the cracks or pits usually found on the pavilion with a substance having a close refractive property of the stone—to make it look less visible. Good lighting, color contrast, presence of gas bubbles at the junctions of the filling were sufficient to prove it was filled. She had no problem with the samples.

Manuel showed her some irradiated samples, but detection was virtually impossible. The samples he had were experimental lab samples. Sophisticated tools were required, but she knew how they looked under different lights. Another experience.

Manuel paused. She refused to take a break, as food arrived. She wanted to master the skill, collect her fees, and leave the country as soon as possible. She was different. Now came the important and most difficult part. Synthetics and simulants.
Manuel had brought in five boxes—full of synthetics and simulants. He had samples, which were cut like their natural counterpart to fool the novice and machine-cut samples, which were less precise. Synthetic flame-fusion blue sapphires weren’t that difficult. He had samples, which were clean and included. The included samples were loaded with gas bubbles, curved lines, and color banding. The clean samples were difficult to identify with a loupe and microscope. The included ones weren’t that difficult. The inclusions were too obvious.

But synthetic flux blue sapphires were difficult. The flux inclusions looked similar to their natural counterpart. Fingerprints, crystals were ditto. The absence of silk (needle-like inclusions) was one clue for identification. The most excruciating experience was when Manuel showed surface diffusion-treated synthetic blue sapphires (flame-fusion) samples. She spent more time recognizing the color features, which were quite different from other samples. Rudy and James reminded Ms Jambo to take her time to feel the samples. With the help of microscope and an immersion cell she studied the curved lines, bands, bubbles, and unmelted particles, which could have fooled her instantly, if she was absent-minded. The color bleeding at facet junctions was a stark reminder. Manuel took his time showing color slides to emphasize the importance. Even though in the trade surface diffusion-treated blue sapphires were getting more or less accepted, synthetic flame-fusion surface diffusion-treated samples were not accepted. Anyone who sold those qualities had only one interest—clean deception. She compared the samples with natural, heat-treated, and synthetic flame-fusion and flux—to see the difference. It was a virtual nightmare.

Their attention moved to other synthetics and simulants. The blue gem materials were easy to identify by their color, inclusions, refractive index (RI), specific gravity (SG) and spectrum. He displayed a gem identification chart explaining the possibilities.


Spinel
polariscope, refractive index specific gravity, inclusions, spectrum

Synthetic spinel
polariscope, refractive index specific gravity, inclusions, spectrum

Zoisite
polariscope, refractive index, specific gravity, inclusions, trichroism

Syn.cubic zirconia
polariscope, specific gravity, dispersion, inclusions

Zircon
polariscope, specific gravity, spectrum, doubling

Tourmaline
polariscope, refractive index, specific gravity, pleochroism, doubling

Beryl
polariscope, refractive index, specific gravity, inclusions

Topaz
polariscope, refractive index, specific gravity, cleavage

Quartz(dyed)
polariscope, refractive index, specific gravity, dye

Synthetic quartz
polariscope, refractive index, specific gravity, unnatural color

Iolite
polariscope, refractive index, specific gravity, pleochroism

Glass
polariscope, refractive index, specific gravity, inclusions

After testing the samples several times, she got a feel for the blue gem materials, but her main headaches were differentiating natural from heat-treated, surface diffusion-treated synthetic flame-fusion and synthetic flux specimens. And finally, he showed her a few samples of synthetic hydrothermal blue sapphires from Russia; synthetic flame-fusion blue sapphires induced with fingerprints, and synthetic flux overgrowth on flame-fusion seed. They were difficult to identify with a loupe or even with a microscope.

After Rudy’s persistent request, Ms Jambo decided to take a break. Manuel looked exhausted after the deliberation. But he had one comment. She had the gemology genes. He had trained several nationalities of different temperament before, but she was different. They were to continue the same exercise for one more day, before the finale. Manuel had already prepared a few test stones.

As James was conversing with Ms Jambo, Rudy was talking on his cell-phone to Julian Tsang. It was going to be his last gamble.