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.

Sapphire:

An ancient Persian legend states the Earth rests on a gigantic sapphire that gives its blue reflection to the sky. The most popular colors for sapphires range from light blue to a blue that appears black. Hence, the name was derived from the Latin form of the Greek word for blue, “sapphirus.” Bright daylight makes most sapphires shine more vividly than the somewhat muted artificial light. So the most highly cherished color for blue sapphires is not the darkest blue, but a deep and satiated blue, which even in dim, artificial light remains to appear blue.

While sapphires are best known for being velvety blue, it was decided long ago to consider all gemstones of the mineral family corundum to be sapphires. Non-blue sapphires are termed “fancy” and can be nearly any color, including yellow, green, white/colorless, pink, orange, brown, purple, golden and even black. Red corundum is the exception, however, and was given the special name of “ruby.” Since pink is really just a light red, the International Colored Gemstone Association has resolved to consider light shades of the red hue to be included in the category ruby, as it is too difficult to legislate where red ends and pink begins. In practice, however, pink shades of corundum are known as either pink ruby or pink sapphire. All sapphires rank a 9.0 on the Mohs Scale, second only to diamonds in hardness.

There are a great number of varieties of sapphire, many of which are quite rare and highly sought-after in the gemstone market. A rare orange-pink variety, known as padparadscha, can be even more valuable than blue sapphire. Pronounced PAD-PA-RAD-SHAH, the name comes from the Sinhalese word for lotus blossom. Endowed with both pink and orange color components, its hues range from pastels to fiery shades. Padparadscha sapphires are usually heat treated to improve and intensify their color, while the color of untreated stones will fade over time. An untreated padparadscha sapphire that has faded will return to its original pinkish-orange color, however, if exposed to sunlight for about an hour.

Another rare variety of sapphire is known as the color-changing sapphire. This stone exhibits different colors in different light. In natural light, color-changing sapphire is blue, but in artificial light, it is violet.

For experts and connoisseurs, the Kashmir-color is considered the most beautiful and valuable shade. It features a pure and intensive blue, which is enhanced by a fine, silky gloss. Its color does not change in artificial light, but remains intense with a deep, velvety sheen. Setting the standard for the color of top-quality sapphires, Kashmir sapphires were found in 1880 after an avalanche. They were intensely mined for only eight years until the source was depleted. The Burma-color is also considered especially valuable, ranging from rich royal blue to deep cornflower blue. Ceylon sapphires are prized as well for the luminosity and brilliance of their light to medium blue color.

There is a translucent variety of sapphire, called star sapphire, which displays a six-point star when cut into a smooth domed cabochon. The mineral rutile is embedded in an asterisk-shape within the stone, causing light to reflect in a phenomenon called “asterism.” Six- or twelve-ray stars appear to magically glide across the surface of the stones as they are moved. Star sapphires and rubies are expensive rarities and should always display the stars exactly in the center of the gem. Value is influenced by the intensity of the body color and the strength and sharpness of the star. The star stone is said to be the home of each person’s angel, who lives there in contentment with the sapphire’s spirit.

The stone is mined in many parts of the world. The oldest sapphire mines are situated in Ceylon, today called Sri Lanka, where gemstones were mined in ancient times. Most blue sapphires today come from Thailand or Australia, but sapphires from Kashmir and Myanmar (formerly Burma) are considered the most rare and highly prized. Sapphires are readily available in sizes of up to 2.00ct, but gems weighing 5.00-10.00ct are not unusual. The cushion-cut Logan Sapphire from Sri Lanka weighs an astounding 423.00ct and can be seen at the Smithsonian Institution in Washington, D.C. There is also a 258.00ct stone set in the Russian crown, which is kept in the Diamond Fund in Moscow.

Because the gem has long symbolized sincere love and enduring faithfulness, blue sapphires are often given in engagement rings to express commitment and loyalty. Many women throughout the world decide on the blue stone for their engagement rings, as the gem also represents truth, friendship, harmony and consistency. Sapphire blue has become a color related to anything permanent and reliable, making it an ideal stone to symbolize the promise of marriage.

Often referred to as “Gem of the Heavens,” sapphire also symbolizes a noble soul. It is September’s birthstone and is traditionally given as 5th and 45th wedding anniversary gifts. Star sapphires are given for the 65th anniversary. The color sapphire-blue is known for representing clarity and competence. In fact, the first computer to ever declare victory over a chess grandmaster and world champion was named “Deep Blue.”

Sapphires have been associated with magical powers throughout the ages. The Greeks identified white sapphires with Apollo and the oracles at Delphi used them to tap into the subconscious and super conscious. During the Middle Ages, sapphires symbolized the tranquility of the heavens and wearing them was thought to bring peace, happiness and purity of the soul. The color blue became the symbol of the union between a priest and the heavens, so sapphires came to be adorned on the rings of bishops. Soldiers wore them to prevent capture by enemies and kings wore the gemstone to defend against harm and put themselves in divine favor. This supposed “divine favor” is why sapphires were often the gemstone of choice for high priests and royalty throughout history. In fact, the British Crown Jewels contain a number of notable sapphires.

Today, sapphires are still believed to hold special powers. The stone is said to provide healing properties for mental illness and depression. It can be considered an aid to psycho kinesis, telepathy and clairvoyance, while providing spiritual enlightenment and inner peace. White sapphires, like diamonds, are considered the guardians of love, enhancing it and ensuring fidelity in marriage. The most powerful type of the gem is said to be the star sapphire. They are believed to protect against negative energy and have a calming effect that allows the mind to experience tranquility, joy and clear thinking.