Sapphire blue gemstone

Blue sapphire, a variety of corundum, is one of the world's most valuable gemstones, prized for its intense color and durability.

About this subject

Blue sapphire belongs to the corundum family, a mineral composed of aluminum oxide. Its characteristic blue color results from trace amounts of iron and titanium in its crystal structure. With a hardness of 9 on the Mohs scale, it is the second hardest gemstone after diamond, making it ideal for everyday jewelry.

The most famous deposits of blue sapphire are in Kashmir (India), Myanmar (Burma), Sri Lanka, and Madagascar. Kashmir sapphires, discovered in the late 19th century, are legendary for their intense velvety blue, but the original mine has been depleted for decades. Sri Lankan sapphires are known for lighter hues and are often heat-treated to enhance color.

Historically, blue sapphire has been associated with royalty and clergy. Sapphire rings adorn members of the British royal family, such as Princess Diana's engagement ring, now worn by Kate Middleton. In medieval times, the gem was believed to protect against envy and harm, and it symbolized wisdom and purity. Today, sapphire is the birthstone for September.

Most commercial sapphires undergo heat treatment to improve color and clarity, a practice widely accepted when disclosed. Untreated natural sapphires are rare and command astronomical prices. Synthetic sapphires, produced in laboratories since the early 20th century, are used in industrial applications and low-cost jewelry.

Frequently Asked Questions

What is the difference between natural and synthetic sapphire?

Natural sapphires are formed over millions of years in the Earth's crust and may contain inclusions. Synthetic sapphires are lab-created with the same chemical composition and crystal structure, but are usually more flawless and much cheaper.

Are blue sapphires always heat-treated?

No, but most commercial blue sapphires undergo heat treatment to enhance color and clarity. Untreated sapphires are rare and more valuable.

What is the most famous blue sapphire in the world?

The Logan Sapphire, 423 carats, on display at the Smithsonian, is one of the most famous. Another is the Star of India, 563 carats, at the American Museum of Natural History in New York.