Ruby red gemstone

Ruby is a red variety of corundum, with a hardness of 9 on the Mohs scale, prized for its beauty and rarity in jewelry.

About this subject

Ruby is one of the world's most valuable gemstones, belonging to the corundum family (aluminum oxide). Its intense red color is caused by chromium impurities in the crystal lattice, and its hardness of 9 on the Mohs scale is second only to diamond, making it extremely scratch-resistant. Major historical sources include Myanmar (formerly Burma), Thailand, Sri Lanka, and Madagascar, with additional deposits in Kenya, Tanzania, and Afghanistan. Burmese ruby, especially from the Mogok region, is considered the finest, with "pigeon's blood" color being the highest quality standard.

Culturally, ruby holds great significance across civilizations. In ancient India, it was called "ratnaraj" (king of gems) and believed to protect its wearer. In the Bible, it is mentioned as one of the stones in the high priest's breastplate. Today, it is the birthstone for July and the symbol of the 40th wedding anniversary. Beyond jewelry, synthetic rubies have been produced since the late 19th century, mainly for use in watches and lasers due to their ability to emit coherent light.

Interesting facts include that natural rubies often contain rutile needle inclusions, forming a "silk" effect that, when cut en cabochon, produces asterism (a star). The largest known star ruby is the "Star of India" at 563 carats, though it is actually a star sapphire. Genuine rubies over 5 carats are extremely rare and can fetch higher prices than diamonds of equivalent size at auctions.

Frequently Asked Questions

What is the difference between ruby and sapphire?

Both are varieties of the same mineral, corundum. Rubies are red due to chromium; all other colors of corundum are called sapphire, including blue, pink, yellow, and green.

How to tell a natural ruby from a synthetic one?

Natural rubies usually have inclusions and irregularities, while synthetics may have bubbles or curved growth lines. A gemologist uses loupes, spectroscopes, and other tests to distinguish.

What does 'pigeon's blood' mean for rubies?

It is the term for the most prized red color, a vivid red with a slight bluish tinge, resembling pigeon blood. It is rare and very expensive.