Ruby red gemstone

Ruby is a red variety of the mineral corundum, highly prized for its hardness and intense color, serving as July's birthstone.

About this subject

Ruby is one of the world's most precious gemstones, belonging to the corundum family, the same species as sapphire. Its vivid red color results from chromium impurities within its crystal structure. On the Mohs scale, ruby ranks 9 in hardness, second only to diamond, making it highly durable for everyday jewelry.

Major ruby deposits are found in Myanmar (formerly Burma), which produced legendary stones like the Sunrise Ruby. Other significant sources include Mozambique, Thailand, Sri Lanka, and Madagascar. High-quality rubies with few inclusions and a pigeon blood red color are exceedingly rare and can command higher prices per carat than diamonds.

Culturally, ruby symbolizes passion, protection, and prosperity. In ancient India, it was called the "king of gemstones" and believed to grant invincibility. Traditional medicine used it to treat heart and circulation issues. Today, ruby is the birthstone for July and the traditional gift for 15th and 40th wedding anniversaries. Synthetic rubies, identical in chemistry to natural ones, are produced in labs and offer an affordable alternative, though they lack the historical prestige.

Interestingly, rubies and pink sapphires are the same mineral species, distinguished solely by color. Commercially, any red corundum is deemed ruby, while all other colors are sapphires. Star rubies, exhibiting asterism (a star-shaped reflection), are cut as cabochons and reveal this phenomenon under direct light.

Frequently Asked Questions

How are rubies formed?

Rubies form in metamorphic rocks under high pressure and temperature, when chromium replaces aluminum in the corundum structure. This occurs in tectonically active regions with intense geological folding.

What is the difference between ruby and pink sapphire?

Both are corundum. The distinction is color: ruby is red (due to chromium), while pink sapphire has traces of chromium and iron. Commercially, red corundum is ruby; all other colors are sapphires.

What is the most famous ruby in the world?

The Sunrise Ruby, a 25.59-carat gem sold for US$ 30 million in 2015, is among the most famous. Another is the Star of India ruby, a 563-carat star ruby displayed at the American Museum of Natural History.