Ruby

Ruby is a beautiful bluish-orange to blood-red gemstone that comes from a mineral called corundum, which is made of aluminium oxide. It is one of the most popular gems used in jewelry and is very tough and strong. Other types of gem-quality corundum are called sapphires, and sometimes rubies are known as "red sapphires".

Ruby is one of the traditional cardinal gems, along with amethyst, sapphire, emerald, and diamond. The name ruby comes from the Latin word ruber, meaning red, because of its bright red color. This special color comes from a metal called chromium mixed inside the stone.

The value of a ruby depends on its color, how it is cut, and how clear it is. The most valuable rubies have a bright red color called "blood-red" or "pigeon blood". Ruby is the traditional birthstone for the month of July. One of the most famous and valuable rubies ever sold is the Estrela de Fura, which was sold for over thirty-four million dollars.

Physical properties

Rubies are very hard gems, scoring 9 on the Mohs scale. Only moissanite and diamond are harder. Rubies get their red color because of tiny bits of chromium in their structure.

When light hits a ruby, it can glow red, a property called fluorescence. This makes the ruby's color even brighter. Natural rubies often have tiny lines inside them called "silk," which help experts tell real rubies from fake ones. Sometimes, rubies can show a starry pattern when cut in a special way.

Occurrence and mining

Rubies have been found and mined in many places around the world, including Thailand, Cambodia, Afghanistan, Australia, Brazil, Colombia, India, Namibia, Japan, and Scotland. After World War II, new ruby deposits were discovered in Madagascar, Mozambique, Nepal, Pakistan, Tajikistan, Tanzania, and Vietnam.

Today, the Montepuez ruby mine in Mozambique is one of the most important sources of rubies. Discovered in 2009, this mine has quickly become the world's top producer of gem-quality rubies. Rubies from North Macedonia are special because they have a unique raspberry color. Some rubies have also been found in the United States, in states like Montana, North Carolina, South Carolina, and Wyoming.

Factors affecting value

Rubies, like other gemstones, are judged based on four main qualities: color, cut, clarity, and weight. The place where a ruby comes from also affects its value.

Color

Color is the most important quality for colored gemstones. Color has three parts: hue, saturation, and tone. Hue is the basic color we see. Rubies are defined as red, while other colors of the same material are called sapphires. Rubies can have hints of orange, purple, violet, or pink in their color.

Clarity

Rubies often have small flaws inside them called inclusions. These are checked for size, number, place, and how easy they are to see. The clearest rubies, called “eye-clean,” have inclusions that are hard to see without a magnifying glass. Some rubies have thin lines of inclusions called silk. Silk can make the gem look brighter and can also show if the ruby has been treated with heat before.

Treatments and enhancements

It is common to improve the quality of gemstones, including rubies, by treating them. One common way is to use heat, which helps change the color and remove unwanted patches or lines in the stone. This heating usually happens at very high temperatures.

Another way to improve rubies is by filling cracks inside the stone with a special kind of glass. This makes the ruby look clearer and better for use in jewelry. The process has several steps, including cleaning the stone, heating it to remove impurities, and then filling the cracks with glass powder. Sometimes, extra materials are added to the glass to give the ruby a specific color. These treatments can make the ruby look much better and clearer.

Synthesis and imitation

In 1837, scientists began making artificial rubies by mixing special materials at high temperatures. By 1903, a man named Verneuil found a way to make rubies on a large scale. Today, synthetic rubies can be made in different ways, and they are often used in technology, like in lasers.

Some rubies are imitated using other colorful stones or glass. These imitations can sometimes confuse buyers, so experts work to help people tell the difference.

Records and famous examples

• The Smithsonian's National Museum of Natural History in Washington, D.C., has some of the world's largest and finest ruby gemstones. One famous ruby is 23.1 carats and was donated by a businessman in memory of his wife. It has a rich red color and comes from the Mogok region of Burma, now called Myanmar.
• In 2007, a London jeweler showed a heart-shaped ruby that weighed 40.63 carats on their website.
• In 2011, the jewelry collection of actress Elizabeth Taylor was sold at an auction by Christie's. Some ruby pieces sold for very high prices, with one ring selling for over US$4.2 million.
• The Liberty Bell Ruby is the largest ruby ever found. It was stolen in 2011.
• The Sunrise Ruby was once the most expensive ruby and colored gemstone in the world, selling for US$30 million in 2015.
• A synthetic ruby crystal was used in the world's first optical laser, built by Theodore H. "Ted" Maiman in 1960.

Historical and cultural references

Rubies have been treasured for a very long time. About 200 BC, rubies were traded along an ancient path called the North Silk Road in China. In many Asian countries, rubies were worn by important people and placed under buildings for good luck.

In Hindu beliefs, rubies are connected to the Sun and a heavenly leader. In comic books, a ruby called the Godstone turned a character into a wolf when moonlight touched it. In the famous 1939 film The Wonderful Wizard of Oz, the main character wears magical ruby slippers that were originally silver in the book but changed to rubies in the movie to show off colorful film technology.