As the gem of spring, emerald is the perfect choice as the birthstone for the month of May. It’s also the gem of the twentieth and thirty-fifth wedding anniversaries. Emerald is the most famous member of the beryl family, a species that includes aquamarine as well as beryls in other colors. Gem experts differ on the degree of green that makes one stone an emerald and another stone less-expensive green beryl. Chemically pure beryl is colorless, but trace elements give rise to various colors. For example, emerald(green) is colored by chromium or vanadium. Aquamarine(greenish-blue to blue) and heliodor(Yellow) are both colored by iron, and morganite(pink to peach) is colored by manganese. The most desirable emerald colors are bluish-green to green, with strong to vivid saturation and medium to medium-dark tones.
The first known emerald mines were in Egypt. dating from at least 330 BC into the 1700s. Cleopatra was known to have a passion for emeralds and used them in her royal adornments. Legends endowed the wearer with the ability to foresee the future when an emerald was placed under the tongue, as well as to reveal the truth and be protected against evil spells. Emerald was once also believed to cure diseases like cholera and malaria. Wearing an emerald was believed to reveal the truth or falseness of a lover’s oath as well as make one an eloquent speaker.
Color: Vibrant green
Refractive Index: 1.577 to 1.583
Birefringence: 0.005 to 0.009
Specific Gravity: 2.72
Mohs Hardness: 7.5 to 8 on the Mohs scale
Treatment: Filling fractures with colorless oil (resin and polymer) can improve an emerald's color by making it look deeper and more even. Also occasionally dyed to improve color uniformity.
Sources: Afghanistan, Brazil, Colombia, Pakistan, Zambia, and Zimbabwe.
Stability: Heat can damage emeralds, especially by extending existing fractures. Light and chemicals can cause the oils, resins, and polymers used to fill surface-reaching fractures to alter in appearance or deteriorate.
Care and Cleaning: Some estimates state that 90 percent or more of emeralds are fracture-filled. Since the great majority of fashioned natural emeralds contain filled fractures, it’s risky to clean them ultrasonically or with steam. Ultrasonic vibrations can weaken already-fractured stones, and hot steam can cause oil or unhardened resin to sweat out of fractures. Using warm, soapy water coupled with gentle scrubbing is the safest way to clean emeralds.