Gemstones are loved by everyone. But they are loved primarily due to one agent i.e. light. Remove it and all the love for gemstones will vanish.
Light illuminates the gemstone in numerous ways. When it passes through them, distinct outlines are formed and multi-colored rays are emitted that enhance a gems’ beauty. To speak technically, these effects are caused naturally due to refraction, reflection, and interference.
Master gem cutters aren’t just slicing and shaping the gemstones; there’s a lot more to it than we can imagine. A certain level of physics is involved behind the whole process, which is used to enhance the refraction of a gem’s surface.
Some of the effects formed when light falls on a gemstone’s surface are highlighted below:
Chatoyancy – the slit of the cat’s eye – is a lighting effect formed when tiny fibers or needles naturally get arranged in a parallel configuration.
If the gem is cut in a convex style (cabochon), the base becomes parallel to the fibers. It reflects a single bright line that moves along the gemstone’s surface when the stone is rotated.
Asterism effect takes place in a gemstone with rutile inclusions. The mineral composites are aligned at various angles depicting a star-like glow when light shines on its surface.
The gemstone needs to be cut in a cabochon style to exhibit such a state. It can exhibit four, six or 12 rays depending on the number of rutile inclusions.
Star sapphires & star rubies are the prime examples of asterism. There is a sapphire named ‘Star of India’ at the American museum of Natural history that weighs 563 carats and is the biggest sapphire featuring asterism phenomenon.
This phenomenon occurs in gemstones having lamellae structure. In lamellae, the layers are formed in the shape of gills; one before the other. A prime example of this phenomenon is moonstone. When light passes through moonstone, a blue-white dichroic film appears on the surface.
Aventurization is a natural metallic glitter formed in some minerals due to tiny reflective mineral platelets. This effect can be made artificially by producing cracks in a rock. Similarly, it can also be formed in opaque minerals due to the presence of small leaf-like inclusions of hematite, fuchsite or goethite.
It is the metallic appearance of blue & golden colors on Labradorite’s surface due to the interference of light with twinned layers of its crystals. The lamellae structure of labradorite limits the light glow but enhances its direction. Labradorescence can also appear on the surface of other feldspars.
Opalescence is the formation of pearl-like appearance on crystals. It is formed as a milky blue hue on the surface of a gemstone mainly due to the short wavelength of light that strike its surface. However, it should not be mixed with opalization.
Opalization is the dynamic change of color by light’s angle variation. The phenomenon usually occurs due to the presence of clusters of microscopic cristobalite spheres inside the silica gel.
Luminescence is the emission of visible light from a gemstone if exposed to certain rays. It occurs when ultraviolet light falls on the surface of a gemstone, also known as fluorescence. Impurities in the metallic surface of uranium, manganese, cobalt and others can also lead to Luminescence.
Want to know more about enhancing your gem’s visual appeal? Stay tuned for more tips, tricks, and lifehacks to keep your jewels shining brightly.