Gemstone Windows and Dark Patches: What to Look for in a Cut Gem

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AI-generated educational illustration. Conceptual only; not a photograph of an actual specimen or location. A coloured gem may have a pale, see-through centre or areas that look almost black. Both affect its appearance, but they do not have the same cause. What is a window? A window is an area where light passes through the gem instead of being returned towards the viewer. You may see the background through it, especially near the centre. Cutting angles and the material's refractive index—how it bends light—help determine whether this happens. There is no single ideal depth for every gemstone. Why dark patches need a closer look Darkness can have several causes. The material may absorb a lot of light. Some facets may reflect dark surroundings or the observer. Extinction is another cause, involving light that is not returned to the viewer after internal reflection. For that reason, calling every black patch “extinction” can be misleading. A simple viewing routine Look at the gem fac...
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Lapis Lazuli Details

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Lapis Lazuli


Lapis Lazuli is a blue rock composed mainly of lazurite and calcite. It is a metamorphic rock that is formed by the contact between limestone and other rocks. Lapis Lazuli has been used for thousands of years as a gemstone, a pigment, and a decorative material. It is found in many parts of the world, including Afghanistan, Chile, Russia, and the United States.

Lapis Lazuli is a popular gemstone because of its beautiful blue color and its relative softness. It is often used for beads, cabochons, and carvings. It is also used for making jewelry, such as necklaces, bracelets, and earrings. Lapis Lazuli was often used in ancient times to make amulets and talismans.

Lapis Lazuli has been used as a pigment since ancient times. It was ground into a fine powder and used to make the famous "ultramarine" blue pigment. Ultramarine was used by many famous painters, including Leonardo da Vinci and Michelangelo.

Lapis Lazuli is a rock that is associated with many myths and legends. It was believed to have magical powers and was used by many ancient civilizations for healing and spiritual purposes. It was also associated with the gods and was often used to make statues and other religious objects.

Sources of Lapis Lazuli include Afghanistan, Chile, Russia, and the United States. Lapis Lazuli is a relatively rare and valuable gemstone. It is often imitated by other blue stones, such as dyed howlite and dyed jasper.


Gemstone Jewelry

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