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