September 11, 2019

If your birthday is in September, your birthstone—the gem associated with the month of your birth—is the sapphire. The sapphire, a variety of the mineral corundum, is a hard and clear gem. The best known sapphires are blue. Their color results from small amounts of iron and titanium in the stone. Sapphires are also found in many other colors, including yellow, green, white, black, violet, and orange. The red variety of corundum is known as a ruby, the birthstone of July. Sapphires have long been used in jewelry and decorative objects.

Sapphires are shown cut and polished, left, and uncut, right. The sapphire is the birthstone of the month of September. Credit: © Biophoto Associates/Photo Researchers

Traditionally, sapphires symbolize faithfulness, nobility, purity, and sincerity. Sapphires were once thought to allow clarity of mind and to ward off evil spirits. As the stone of the planet Saturn, sapphires offered a magical portal to heavenly realms. In ancient Greece and Rome, sapphires protected people from envy and harm. The gems have long been popular with royalty, and Roman Catholic bishops and other clergy have worn sapphire rings for centuries. The sapphire’s rich blue color is used to describe blue objects of particular beauty, such as Sapphire Lake in northern California. The sapphire is the traditional gem gift for a 45th wedding anniversary. In 2017, Queen Elizabeth II became the first British monarch to mark a 65th year on the throne with a sapphire jubilee.

The most valuable sapphires once came from Indian Kashmir. They are a magnificent cornflower blue, the color to which all sapphires are compared. Today, Thailand is the most important source of blue sapphires. Blue and fancy sapphires are also found in the Sapphire Mountains (naturally) of Montana and in Australia, Myanmar, and Sri Lanka.

Lovely star sapphires contain needles of the mineral rutile that reflect light in six starlike rays. The most highly prized star sapphires are blue. Black or white star sapphires are less valuable. One of the largest blue star sapphires, the Star of India, weighs 563 carats, or about 4 ounces (110 grams). It is on exhibit in the American Museum of Natural History in New York City.

Click to view larger image
Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

July 5, 2019

If your birthday is in July, your birthstone—the gem associated with the month of your birth—is the beautiful and valuable ruby. A red gem variety of the mineral corundum, rubies are called sapphires if they are any color other than red. Since ancient times, rubies have been treasured for their beauty as well as their symbolic value in folklore, religion, and superstition.

The ruby, the birthstone for July, is often used to make jewelry such as rings. This ring is set with a ruby and diamonds. Credit: © JupiterMedia/Alamy Images

Early cultures valued rubies for their resemblance in color to human blood, and the gems were thought to hold the power of life. Rubies were later associated with beauty, love, passion, wealth, and wisdom. Ancient Sanskrit texts refer to the ruby as “the king of precious stones,” and Hindu legend says that those who offered rubies to the god Krishna were granted rebirth as emperors. Rubies were thought to protect those who wore them, even bestowing invincibility in battle. It was not enough to simply wear rubies, however—they were often inserted in the skin. Rubies were also sometimes included in the foundations of buildings to ensure good fortune. Rubies have long adorned earrings, necklaces, rings, and other jewelry, and they are the traditional gift for a 40th wedding anniversary.

Chemically, a ruby is an aluminum oxide. Rubies get their color from traces of chromium. The red of most rubies has a brownish or yellowish tint. The rarest, most highly prized rubies are pure “pigeon-blood red.” Rubies and sapphires are second only to diamonds in hardness, and fine-quality rubies are among the costliest of all gems. The finest rubies come from Myanmar. Other primary producers of rubies are Cambodia, Kenya, Madagascar, Tanzania, Thailand, and Zimbabwe.

A star ruby cabochon shows a six-rayed star within it when seen in a bright light. A cabochon is a rounded, polished stone. The largest known natural ruby, named the “Eminent Star,” weighs 6,465 carats, or almost three pounds (1.36 kilograms). Millions of carats of inexpensive synthetic rubies are made each year. But a demand for real gems has allowed the natural stones to maintain their high value. It can be hard to distinguish between natural and synthetic rubies, even for experts. Experts are also challenged when determining whether the color of a natural ruby has been improved by heating.