a subsurface feather in diamond resembling an insect wing, with visible iridescence caused by thin-film interference. photomicrograph by matthew hardman; field of view 2.90 mm.
The pinnate cracks under the near-surface of a diamond resemble the wings of an insect and form an iridescent color due to the interference of the film. Sightshed 290mm。
diamond is very resistant to scratching and is often referred to as the hardest mineral on earth due to its compact crystal structure. however, diamond is not indestructible, and it can be fractured or even broken apart during ascent from the mantle to the earth’s surface through fast, violent kimberlite eruption. collision with rocks in high-energy rivers also results in percussion marks on the surface of alluvial diamonds (e.g., j.w. harris et al., morphology of monocrystalline diamond and its inclusions,” reviews in mineralogy and geochemistry, vol. 88, no. 1, 2022, pp. 119–166). surface cracks extending into the interior of a diamond are referred to as “feathers” in the gem trade, and these often h**e a negative effect on the clarity grade.
Diamonds are the hardest minerals on earth due to their tight crystal structure and extremely high resistance to wear and tear, however, diamonds are not indestructible, and in the process of rising from the mantle to the surface, diamonds may produce cracks and even rupture due to the rapid and violent eruptions of kimberlite. Collisions with rocks in high-energy flowing water can also cause alluvial marks on the surface of diamonds. In gemstones**, surface cracks that extend into the interior of a diamond are called "feathers" and often have a negative impact on a diamond's clarity grade.
fractures within diamond can cause fascinating optical phenomena on rare occasion. the authors recently examined a 0.39 ct fancy deep brownish yellowish orange type ib/iaa diamond containing multiple feathers and graded as i2 clarity. these natural features had not been filled with a clarity-enhancing material. the largest feather located on the table facet of the diamond resembled an iridescent insect wing (see above).
Fractures in the interior of a diamond can produce fascinating optical phenomena in rare cases. The authors recently tested a piece weighing 0A 39 carat IB IAA factual deep brownish-yellow-orange diamond with multiple feathers on the inside and an I2 clarity. This natural feature is not filled with material to enhance clarity. The largest feather crack is located on the diamond countertop, resembling rainbow-colored insect wings.
iridescence is an optical phenomenon caused by interference of light, typically seen in gemstones with cle**age or repeating submicroscopic structures (e.g., x. lin and p.j. heaney, “causes of iridescence in natural quartz,” spring 2017 g&g, pp. 68–81). in this diamond, the feather’s iridescence was due to thin-film interference caused by a thin film of air with a thickness similar to the w**elength range of visible light. as diamond and air h**e very different refractive indices, there is a phase difference between the incident light reflected from the upper and lower boundaries of the thin film, resulting in constructive and destructive interference. when viewed using a broadband light source (light consisting of a wide range of w**elengths), constructive or destructive interference intensifies or attenuates certain w**elengths (colors), respectively, producing a rainbow-like interference pattern.
Iridescent colors are caused by the interference of light and are usually found in gemstones with cleavage or repeating submicroscopic structures. In this diamond, the iridescent color of the plume is caused by the interference of a thin film of air with a thickness similar to the wavelength of visible light. Due to the large difference in the refractive index values between diamond and air, there is a phase difference between the incident light reflected from the upper and lower boundaries of the film, resulting in the interference of light. When observed with a light source with a wide wavelength, constructive and destructive interference increases or decreases the silent wavelength, respectively, resulting in a rainbow-shaped interference pattern.
Okay, that's all for today's story, I'm Ai Hao, a jewelry appraiser, a Ph.D. in archaeology, I hope it will be helpful to you.