A raw sapphire refers to the gemstone in its natural state, directly from the earth, before any cutting, polishing, or treatment. Unlike the sparkling, faceted gems often seen in jewelry, a raw sapphire exhibits a different appearance. It retains its original form and texture as shaped by geological processes, providing insight into its natural formation.
Understanding Raw Sapphire Colors
Raw sapphires display a wide spectrum of colors, extending far beyond the well-known blue. These gems, a variety of the mineral corundum, naturally occur in hues such as pink, yellow, green, orange, purple, black, or colorless forms. While a cut sapphire showcases vibrant color through its facets, the color in a raw sapphire often appears more muted or uneven. This difference is due to the absence of light reflection from polished surfaces and the common presence of internal features.
The color distribution within a single raw sapphire can also vary, sometimes showing different hues or color zoning. Raw sapphires might appear opaque or translucent rather than transparent, especially if they contain numerous inclusions. The true vibrancy of their color is often only fully revealed after cutting and polishing.
Crystal Shapes and Formations
Raw sapphires typically crystallize in distinct shapes, reflecting their trigonal crystal system. They commonly form hexagonal prisms with flat basal terminations, or appear as barrel-shaped crystals. These formations show a six-sided structure, sometimes elongated and symmetrical like a pencil. Visible crystal faces indicate the gem’s inherent geometric structure.
Beyond these defined crystal habits, sapphires are also frequently found as irregular, rounded, or water-worn pebbles. This occurs particularly in alluvial deposits, where the gems have been transported and abraded by natural forces like rivers.
Surface Characteristics and Inclusions
The surface of a raw sapphire generally lacks the brilliant sparkle of a cut gem. Its luster can range from greasy or vitreous to dull on unpolished surfaces. The exterior texture varies, sometimes appearing rough, pitted, or etched, and at other times somewhat smooth, depending on its specific formation environment.
Internal features, known as inclusions, are common within raw sapphires and influence their clarity and overall appearance. These can include fine rutile needles, which, when aligned, create asterism, seen in star sapphires. Other common inclusions are gas bubbles, liquid-filled cavities, or tiny crystals of other minerals. These internal characteristics often make the raw stone appear cloudy, milky, or opaque.