Cut: Refers to the geometric shape and proportions of a gemstone. A gemstone’s cut is what most directly affects its sparkle or brilliance.

Facet: A flat cut on the surface of a gemstone.

Fire: Flashes of rainbow colors. Also called “dispersion.”

Hardness: Resistance to scratching. The higher the number, the more resistant.

Hue: Another word for color.

Luster: The shininess of a jewel.

Opaque: The opposite of transparent. Light cannot pass through an opaque gemstone, therefore they do not have any sparkle or fire.

Saturation: This term refers to how pure or deep a gemstone’s color is. Some gemstones, like aquamarine, have a naturally low saturation (very light blue) while other gemstones, like amethysts, can have very high saturation (rich, dark purple).

Sparkle: The white light leaving a jewel, traveling upward, which is visible to the eye. Sparkle is often referred to as “brilliance.”

Toughness: Resistance to breakage.

Gemstone Shapes & Cuts
These are the common shapes or cuts for gemstones, each lending a different look and allure.

Baguette: Baguette means “stick” or “rod” in French, which makes it a very appropriate name for this gemstone shape. Diamond baguettes are often used as accent stones to flank a primary stone.

Brilliant: Any gemstone cut with 58 facets, which produces the maximum possible sparkle. A brilliant cut can have several shapes, including round, oval, pear, radiant and heart.

Cabochon: This shape features a rounded, perfectly smooth surface instead of facets. It is the oldest gemstone shape and is commonly used with opaque stones such as opal, jade and turquoise.

Cushion: A very popular style for most of the 19th century, cushion shapes are slightly domed with rounded corners that make the stone look like a pillow. In fact, this shape is often referred to as a “pillow cut.” It looks particularly beautiful in candlelight.

Emerald: With its long, steep facets, emerald cuts tend to flash rather than sparkle.

Fancy: Technically, this term refers to any type of gemstone that isn’t round, but many jewelers reserve it to describe the more exotic gemstone shapes such as marquise, heart, pear and trillion.

Heart: Often described as a custom cut, heart-shaped gemstones are very popular for pendants.

Marquise: According to legend, this shape was commissioned by King Louis XV to resemble the smile of his mistress, Marquise de Pompadour. Ideal marquise cuts have a length to width ratio of 2:1.

Oval: Similar to the round shape, oval gemstones produce a high amount of sparkle and fire.

Pear: This is a classic teardrop shape that is ideal for earrings and pendants.

Princess: This a relatively new shape that combines the sharp, flat edges of an emerald shape with numerous small facets, which produce both sparkle and fire.

Radiant: This shape is similar to emerald, but it adds extra facets on the edges and corners to increase the gemstone’s sparkle.

Round: This classic shape produces maximum sparkle and fire, making it an ideal shape for diamonds.

Tapered Baguette: A tapered baguette is a baguette shape with one end that is narrower than the other.

Trillion: A very striking, usually three-sided shape, trillion gemstones (especially diamonds) are celebrated for the intense fire they produce.

The Mohs Scale
The most common measure of a gemstone's degree of hardness is based on the Mohs Scale. Devised by German geologist Friedrich Mohs in 1812, the Mohs Scale grades minerals on a comparative scale from 1 (very soft) to 10 (very hard).

Hardness is generally associated with durability and the ability to resist breakage. When referring to gemstones, however, hardness more accurately means the stone's ability to resist abrasion. What the scale means is that a mineral of a given hardness rating will scratch other minerals of the same rating, as well as any minerals of a lower hardness rating. For example, rubies and sapphires, which are composed of the mineral corundum and have a Mohs rating of 9, will scratch each other, as well as topaz (rating 8) and quartz (rating 7). But they will not scratch diamonds, which are rated 10 and considered the hardest substance.

The numeric values assigned to each interval of hardness are not equal. Some stones are disproportionately harder than others. Because Mohs Scale wasn't made for exact precision, it uses half numbers for in-between hardness ratings.

Peridot:

Peridot features a lively yellow-green color that is transparent with an oily luster. The iron that creates peridot’s color is an integral part of its structure, so the gem is only found in various shades of green. It is most prized in lime hues, but Italian peridot is a rich olive color and popular American peridot is a beautiful light yellow-green. The Romans called peridot “evening emerald” because its exquisite green color was said to glow at night. This is perhaps because the stone exhibits double refraction, meaning that when looking through the stone, objects appear double. So when looking into a faceted peridot, the number of bottom facets appears to be double the actual number, creating a glittering sensation.

Pronounced PEAR-A-DOE, the word “peridot” comes from the French word meaning “gem.” It is the gem variety of the mineral olivine and ranks a 6.5-7.0 on the Mohs Scale.

Born in cauldrons of fire, peridot is considered the “volcanic gem,” since small crystals of it are often found in the rocks created by volcanoes. In fact, Hawaiian legend called peridot the divine tears wept by Pele, goddess of the volcano. The island of Oahu even has beaches made out of olivine grains, but they are much too small to cut into peridot. Samples of the gem also have been discovered in meteorites that have fallen to Earth, many of which are more than a billion years old.

Peridot traces its jewelry roots to 3,500 years ago. The stone was first mined by the ancient Egyptians on the volcanic island of Zebargad in the Red Sea. Known as the “serpent isle,” it was infested with poisonous snakes that interfered with mining activity until one Pharaoh had them all driven into the sea. Today, Native Americans mine most peridot on the San Carlos Reservation in Arizona. Interestingly, almost all peridot sold in Hawaii is from Arizona, despite the fact that peridot is produced by Hawaii's volcanoes. The gemstone is also found in Norway, Brazil, China, Egypt, Italy, Myanmar and Sri Lanka. An exciting new deposit was discovered in Pakistan in 1994, yielding some of the finest peridot ever seen, including one stone that weighed more than 300.00ct.

Peridot is among the oldest known stones and has been mined as a gem for thousands of years. As early as 1575 to 1350 B.C., the ancient Egyptians used peridot beads in their ceremonial jewelry. In fact, it is believed the stone was one of the favorite gems of Cleopatra and that some of the “emeralds” she wore were actually peridot.

Ancient Egyptians also carved small drinking vessels out of large chunks of peridot. Priests would drink soma from them in rituals, believing the soma would put them in touch with the nature goddess, Isis. Legend has it that King Soloman traded cedar trees from Lebanon for 12 soma drinking cups and 144 liters of soma. The Egyptians made this trade for ramp logs to build their pyramids at Gisa, while King Soloman was said to have been enlightened by drinking soma from the peridot cups. Today, Mexican hill tribes still drink soma from green glazed cups to put them in touch with nature and their ancestors’ spirits. Additionally, some Native American Indians in Arizona use tea made from peyote ground with peridot crystals in their rituals.

Peridot has also been important to other cultures throughout history. Late in the Ottoman Empire (1300 to 1900), peridot was a highly prized gem and Turkish Sultans amassed some of the world’s largest collections of the gemstone. It is mentioned in the Bible under the name of “chrysolite,” and was used to decorate medieval churches with samples that were most likely carried back to Europe by the Crusaders. Large stones weighing more than 200.00ct adorn the Shrine of the Three Magi at the Cologne Cathedral in Germany.

Throughout the ages, peridot has been believed to hold mystical powers of protection and healing. The ancients regarded the stone as a symbol of the sun and wore it in amulets to prevent nightmares and drive away evil spirits. It was even favored by pirates to protect them against evil. Peridot was said to be useful for calming raging angers, curing nervous afflictions and promoting quiet sleep. It was also used as a medical remedy to treat asthma and ward off fevers. Peridot was also believed to strengthen any medicine drunk from goblets carved from the stone. South American Shamans use peridot to ward off snakebites and the evil spirits who have taken the form of mosquitoes who bring the sleeping sickness. They also say the heating of magic mushroom tea by peridot takes them on trips to the ancestor heavens.

Today, peridot is believed to bring the wearer success, peace and good luck. To be most powerful, it is said that the stone should be mounted in gold and surrounded with small diamonds. With powers that are thought to bring protection and health, modern folklore also says it can be used to attract love and calm anger while soothing nerves and dispelling negative emotions. The gem is believed to protect the wearer from bad dreams when set in gold.

Peridot is considered the birthstone of August. Given as a symbol of fame, dignity and protection, this gem is also traditionally given to couples celebrating their 16th wedding anniversaries.