Geological & Scientific Properties | Ruby
Ruby is a precious gemstone and a variety of the mineral corundum, distinguished by its rich red color, which is primarily due to the presence of chromium. It's one of the most valued gemstones, often prized higher than diamonds of similar size due to its rarity and the vibrancy of its color. Here's an overview of Ruby's geological and scientific properties:
Chemical Composition and Structure:
- Composition: Ruby is essentially aluminum oxide (Al₂O₃) with chromium impurities, which give it the characteristic red color.
- Crystal System: Like all corundum, ruby crystallizes in the trigonal system, forming hexagonal prisms and plates.
Physical Properties:
- Color: The color ranges from pink to blood-red. The most prized rubies are a deep red with a hint of blue, often referred to as "pigeon's blood" rubies.
- Hardness: Ruby is very hard, rating 9 on the Mohs scale, making it the second hardest natural mineral after diamond.
- Luster: It typically has a vitreous luster.
- Transparency: Rubies can range from transparent to opaque, with the most valuable stones being clear and highly transparent.
Optical Properties:
- Refractive Index: The refractive index of ruby ranges from about 1.762 to 1.770, with a birefringence of 0.008 to 0.010.
- Pleochroism: Rubies exhibit strong pleochroism, showing different colors when viewed at different angles – typically a deeper red and a more purplish-red.
Geological Occurrence:
- Formation: Rubies are commonly found in marble and basalt environments. They form under high temperature and pressure conditions, where aluminum and oxygen atoms bond and chromium can be incorporated.
- Associated Minerals: They are often found with other gemstones such as sapphire (which is also a variety of corundum), spinel, and garnet.
Major Deposits:
- Significant sources of high-quality rubies include Myanmar (Burma), Thailand, Sri Lanka, Madagascar, East Africa (Kenya, Tanzania, and Mozambique), and Afghanistan.
Rubies have been revered throughout history in various cultures, often symbolizing wealth, power, and passion. They are a popular choice for engagement rings and other fine jewelry. Due to their hardness, they are also suitable for everyday wear. The value of a ruby is determined by its color, clarity, cut, and carat weight, with color being the most significant factor. High-quality rubies are rare and can command higher prices than diamonds.
