Corundum is a mineral species that can exhibit a variety of red color called ruby, and which is due to the presence of traces of chromium substituting aluminum in its crystal structure. Color saturation can vary, from dark red to light red, or even pink. Experts commonly classify these stones into two categories: rubies and pink sapphires. In addition, ruby ​​exhibits a characteristic red fluorescence which can vary in intensity depending on the possible presence of iron. Ruby is also notable for its hardness, which ranks at 9 on the Mohs scale, just below diamond.

COLOR

Chromium-colored corundum is categorized according to its red saturation, ranging from dark red to light red, ruby ​​or pink sapphire. However, there is no defined chromium concentration threshold to differentiate them. The most reliable method to distinguish these stones is to rely on color by visually comparing with color charts or standard stones exhibiting pleochroic reflection and color effects similar to those of rubies and pink sapphires.

SIZE

Rough rubies are cut into various shapes and sizes depending on the lapidary's intention and the original rough piece. Ruby lends itself to all sizes, but the most popular are the “Oval” and “Cushion” cuts.

Expert lapidaries seek to bring out the most beautiful color possible and minimize material loss during cutting.

CLARITY

The formation of rubies requires many natural elements from the Earth and several years of pressure and natural growth. This growth process involves many earth elements, which can affect the clarity of the stone. During their growing process, rubies can develop fractures and inclusions which impact the color and visibility of the stone.

Many inclusions can be seen in rubies, such as clouds, needles, feathers, crystals, dots, etc. The less the stone has, the higher its quality.

ORIGINS

Asia has long been the main source of rubies, with the Mogok Stone Tract mines in Burma producing precious rubies since the 16th century. Burmese rubies remain highly valued and break record prices at auction. Other mines have been discovered in Burma as well as Sri Lanka, Afghanistan, Pakistan and Thailand. The rubies from these countries all have a history and a particular characteristic.

CHOOSE YOUR RUBY

The choice of a quality ruby ​​depends on several essential criteria. First, examine the color, favoring an intense and uniform red. Transparency is also crucial, so look for stones without inclusions visible to the naked eye. Size matters: opt for a well-cut cut to maximize shine. Carat weight can influence price, but don't sacrifice quality for size. The provenance of the ruby ​​is important, with a preference for stones from Burma, Sri Lanka or Mozambique. Finally, ensure the authenticity of the stone by requesting a gemology certificate.