Ruby

Physical Properties of Ruby

• Ruby has a hardness of 9.0 on the Mohs scale.
• It is one of the hardest natural gems, with only diamond and moissanite being harder.
• Ruby is α-alumina, the most stable form of Al, making it transparent and colorless.
• The crystal structure of ruby is distorted due to the substitution of Al ions with Cr ions.
• Ruby absorbs ultraviolet, violet, and yellow-green light, resulting in its red color.

Color and Quality of Ruby

• The color of a ruby is due to the presence of chromium.
• The highest quality ruby is blood-red or pigeon blood in color.
• Clarity is an important factor in determining the quality of a ruby.
• Treatment of rubies, such as heat treatment, is common in the industry.
• Rubies with no needle-like rutile inclusions may indicate treatment.

Distinction between Ruby and Pink Sapphire

• Gemstone-quality corundum in shades of red, including pink, are called rubies.
• In the United States, a minimum color saturation is required to be called a ruby.
• The distinction between ruby and pink sapphire is subjective and can be debated.
• Trade organizations have adopted a broader definition of ruby to include its lighter shades.
• The International Colored Gemstone Association (ICGA) recognizes pink as a shade of ruby.

Occurrence and Mining of Ruby

• Historically, rubies have been mined in Thailand, Cambodia, Afghanistan, and other countries.
• Ruby deposits were discovered in Madagascar, Mozambique, Nepal, and other regions after World War II.
• The Republic of North Macedonia is the only country in mainland Europe with naturally occurring rubies.
• Rubies have also been found in the United States, specifically in Montana, North Carolina, South Carolina, and Wyoming.
• Spinel, another red gemstone, is sometimes found alongside rubies in the same deposits.

Value and Significance of Ruby

• Ruby is one of the most popular traditional jewelry gems.
• It is a durable gemstone and is highly valued.
• The quality of a ruby is determined by its color, cut, clarity, and carat weight.
• Ruby is the birthstone for July.
• The Sunrise Ruby is the world's most valuable ruby sold at auction.

Ruby Data Sources