What Is a Natural Ruby?

Features

• The color of natural ruby ranges from a light rose pink to deep red, and may have a purple tinge. There are also brownish red rubies.

Composition

• A natural ruby is an form of aluminum oxide, and its chemical formula is Al2O3. The red color of the ruby comes from a small amount of chromium atoms replacing aluminum atoms.

  A natural ruby may have rutile inclusions. When cut right, the rutile can display a star shape in the ruby, making it what is known as a star ruby (a rare kind of ruby). This star-displaying property is known as asterism.

Considerations

• A natural ruby may be heat treated to improve its appearance.

  When a natural ruby is heated to high temperatures, it temporarily turns green.

Location

• Countries known for their natural ruby deposits include Kenya, Somaliland, Malawi, Tanzania, Afghanistan, Madagascar, Australia, New Zealand, China, Nepal, Colombia, Cambodia, Sri Lanka, Thailand, Vietnam, France, Czech Republic, India, Pakistan, Greece, Germany, Norway, Russia, Switzerland, Takjikistan, Greenland and the US.

  The rubies considered the best gem quality come from north-central Burma.

Misconceptions

• Natural rubies can be confused with other red minerals such as red spinels, which are made of magnesium aluminum oxide. It is not uncommon for spinels to occur near rubies.