Fractures are usually not desired in gemstones, but in some cases they provide a great subject for photomicrography. When a 2.49 ct yellow sapphire from Ilakaka, Madagascar, was examined with a fiber-optic light, the scene in the figure above was revealed. It is reminiscent of a long-exposure photograph of a star-filled sky with an extraterrestrial object floating in it. In reality, this is a globular iron stain in a large fracture, but the spotted iron staining evokes a faraway planet. The colorful curved lines are conchoidal patterns in the fracture. The combination of features makes the image seem as if viewed through a telescope rather than a microscope.
Illumination is very important for capturing the iridescence effect. Only if a strong fiber-optic light is used at the correct angle relative to the fracture will the colorful curved lines be highlighted.
Charuwan Khowpong is an analytics technician at GIA in Bangkok.
Fractures are usually not desired in gemstones, but in some cases they provide a great subject for photomicrography. When a 2.49 ct yellow sapphire from Ilakaka, Madagascar, was examined with a fiber-optic light, the scene in the figure above was revealed. It is reminiscent of a long-exposure photograph of a star-filled sky with an extraterrestrial object floating in it. In reality, this is a globular iron stain in a large fracture, but the spotted iron staining evokes a faraway planet. The colorful curved lines are conchoidal patterns in the fracture. The combination of features makes the image seem as if viewed through a telescope rather than a microscope.
Illumination is very important for capturing the iridescence effect. Only if a strong fiber-optic light is used at the correct angle relative to the fracture will the colorful curved lines be highlighted.
Charuwan Khowpong is an analytics technician at GIA in Bangkok.
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