A raw ruby is an uncut, unpolished ruby in its natural state, exactly as it appears when extracted from the earth. Unlike the brilliant, faceted gemstones commonly seen in jewelry, raw rubies possess a much different appearance. This natural form reveals the mineral’s fundamental characteristics before human intervention. Understanding what a raw ruby looks like provides insight into its geological origins and inherent properties.
Appearance of Raw Ruby
Raw rubies display a range of colors, from pale pink to a deep red, often appearing uneven or splotchy. They can have brownish or purplish undertones, typically due to impurities. The highly prized “pigeon’s blood” red, a vivid, pure red with a slight bluish hue, is rare in raw form and usually only apparent after cutting and polishing.
The luster of a raw ruby is often dull, greasy, or earthy, a stark contrast to the brilliant shine of a cut gem; sometimes, on a fresh break, it might exhibit a vitreous, or glass-like, luster. Raw rubies are typically opaque to translucent, rarely transparent. They frequently appear cloudy or contain visible inclusions within their structure. The texture of raw ruby is rough and uneven, sometimes showing striations or growth marks from its formation. Ruby’s hardness is 9 on the Mohs scale, second only to diamond, and it can scratch glass.
Common Forms and Habitats
Raw rubies crystallize in distinct forms. They commonly exhibit hexagonal shapes, appearing as hexagonal prisms or flat hexagonal plates. These crystal habits are often visible even in unrefined specimens.
Rubies are frequently found embedded within a host rock, known as a matrix. Common host rocks include marble, basalt, and gneiss. Within these formations, rubies might appear as small crystals alongside other minerals such as mica, calcite, feldspar, zoisite, or kyanite. Rubies can also be discovered in alluvial deposits, where they exist as weathered, rounded pebbles in riverbeds. In these instances, the original crystal shape may be less defined due to erosion.
Distinguishing Raw Ruby from Similar Minerals
Many red minerals can be mistaken for raw ruby, including red garnet, red spinel, rubellite tourmaline, red jasper, and even stained quartz. Distinguishing raw ruby from these look-alikes involves observing specific physical characteristics and performing simple tests.
Ruby’s hardness of 9 on the Mohs scale is a primary differentiator, as it will scratch most other minerals and glass. In contrast, red garnet ranges from 6.5 to 7.5 on the Mohs scale, and spinel is between 7 and 8. While other minerals can form hexagonal crystals, ruby’s specific hexagonal prism or tabular habit is often a helpful clue. The luster of raw ruby, which can be dull or earthy, also differs from the lusters of other red minerals.
Raw rubies often contain internal features such as fine rutile needles, often called “silk,” or “fingerprint” inclusions, which are characteristic of the gemstone. Some rubies also exhibit a red fluorescence under ultraviolet light due to the presence of chromium, though iron content can reduce this effect. Garnets, conversely, are eye-clean and do not fluoresce. Accurately identifying raw ruby requires professional gemological expertise.