INCLUSION

In horological gemology, an inclusion is any impurity or internal anomaly trapped within a Gem during its natural or synthetic formation. Inclusions can be solid (mineral crystals), liquid (water film), or gaseous (bubbles). Depending on their nature and position, they can diminish or enhance the value of the gem: the Hand of rutile in the Quartz creates asterism (the Star (wheel) effect) sought after in certain stones. In watchmaking, jewel bearings (synthetic Ruby / Jewel) must be practically free of inclusions to ensure a uniform pivot bearing surface and maximum longevity. The Glass (crystal) Sapphire used for watch crystals is a synthetic corundum free of inclusions, its transparency resulting directly from its crystalline purity. Inclusions are also a classification criterion for diamonds used in setting of dials and bezels, according to the GIA scale ranging from IF (Internally Flawless) to I3 depending on the visibility of flaws under tenfold magnification.