The Ultimate Guide to Gemstones

For more than 2,000 years, gemstones have symbolized power, wealth, and authority. Kings once wore them in their crowns and the ancient Egyptians and Romans believed colored stones had healing and spiritual powers. Their popularity continued through the Middle Ages, and today, gemstones still haven’t lost their luster. From diamonds and pearls, to emeralds and aquamarines, gemstones are big business. Whether someone sports a diamond engagement ring on their finger or they keep a piece of amber in their pocket for good luck, gemstones are as popular as ever.

Characteristics and Classification

In basic terms, a “gemstone” is a mineral, rock, or petrified material that can be used in jewelry when it’s cut or polished. They are classified into different groups, species, and varieties. Gemologists classify the stones based on several characteristics. The first includes chemical composition, which means a gemstone may be a pure chemical element like a diamond, or simple compound (a mixture of different compounds & elements) like quartz. Another category is crystal structure, where a stone might have a single or multiple microscopic crystals. Other characteristics gemologists use include: specific gravity, or density; durability, which refers to the hardness and toughness; and optical attributes. The optical attributes consist of color, clarity, fluorescence, optic character, and ways they refract light. In the past, the system wasn’t as ornate. Gemstones fit into a category of either precious or semi-precious stones. The short list of precious stones included diamonds, rubies, sapphires, emeralds, opals, and pearls.

•  A Guide to How Gemstones are Classified.
• Mineral Classification Guide
• Gemstone Chemical Properties
• Gemstone Refraction Index
• The Crystal Structure of Gemstones
• Where Go Gems Form?

The Value of Gemstones

Other than the grading system for diamonds, there are no universally accepted grading systems for any other gemstone. Today, the values of gems come down to four qualities, sometimes known as “the four C’s.” They include color, cut, clarity and carat (size). Still, in today’s market, there are general rules that determine the value of all gemstones: vivid, saturated colors are more highly prized than subdued or grayed-out colors; durable stones are generally more prized than lesser durable stones; rarer stones are more highly prized than common ones; and well-cut stones with good symmetry, attractive designs, and fine polish are more prized than poorly-cut ones. Hollywood can also play a part. Occasionally, some gemstones are in higher demand because celebrities wear them or they’re sold on various television shopping networks. Like any fad, these increases in demand tend to be short-lived. During the last 200 years, there are certain stones (rubies, emeralds, pearls, sapphires, and of course diamonds) whose values haven’t significantly decreased.

• The Guide to Gemstone Pricing
• Gemstone Prices
• Gemological Institute of America

Grading

There are lots of laboratories out there that grade and provide reports on diamonds. Only the American Gemological Laboratories (AGL) grades gemstone quality using a system they’ve developed in the lab. Just like diamonds, gemstones are graded by cut, color, clarity, and carat weight. When grading a gemstone, the gemologist measures its weight in carats and dimensions in millimeters. Since color is the first aspect someone usually notices about a gemstone, it’s measured by three qualities: hue, tone, and saturation. Color is mainly caused by the gem's selective absorption of certain wavelengths of light. Gemologists refer to this color as the gem's “body color.” The Gemological Institute of America (GIA) uses 31 hues to describe color in a gemstone and six saturation measurements ranging from dull to strong to vivid.

• Consumer Guide to Gem Grading
• Gemmological Association of All Japan
• American Gem Society

Cutting and Polishing

When gems are cut and polished, the process is dubbed “gem cutting” or “lapidary.” All gemstones are polished and cut using finer and finer grits of harder substances until the desired shape is reached. Grinding is usually done using a wheel, and some gemstones are even cut by diamonds - one of the hardest substances on the planet. Gemstones are shaped in number of ways, including sawing, grinding, drilling, sanding, or tumbling (turned at a slow speed in a rotating barrel). Stones are usually cut as dome-shaped objects called “cabochons,” or they’re cut with a faceting machine into a symmetrical pattern. The facets or small “windows,” let clearer gems (think diamonds) reflect more light. No matter what the stone is, a well-cut one is symmetrical and reflects light evenly across the surface. Also, the polish is smooth and doesn’t have any nicks or scratches. A good cut always showcases the stone’s color and diminishes its inclusions. Popular cuts include the emerald cut, a rectangular or square step cut with diagonal corners; and the princess cut with lots of sparkling facets.

• The Cuts of Gemstones
• Popular Diamond Shapes
• Gem Cutting
• The History of Lapidary

Gemstone Colors

The color of a gemstone is usually the first aspect of it that meets your eye. It’s the most obvious and attractive feature and everything from the polish to the cut of the stone is meant to pick up color or light. The difference in color is a result of the atomic structure of the stones. Throughout history, the colors of gemstones have come to take on deep meanings, often conveying different states of mind or being synonymous with a certain month. For instance, pink symbolizes love and beauty, while gold translates into wealth, wisdom, and prosperity. Green is one of the more prominent colors in gemstones, appearing in the forms of emerald, jade, tourmaline, peridot, and alexandrite. Ironically, one of the more rare gemstones on the earth, painite, doesn’t have the most attractive appearance. Its brown-ish red color is similar to topaz due to trace amounts of iron. Also, aome gemstones like Alexandrite actually change color depending upon the light it’s viewed under.

• Gemstone Colors
• Causes of Color
• Gemstone Color Meanings
• Colors in Minerals
• Visual Properties of Gemstones

Most Popular Gemstones

It’s probably not a surprise to anyone that diamonds are the most popular gemstones of all-time. Many women have an affinity for all types of diamonds – pale yellow, blue, and pink included – but men still prefer the clear types. Diamonds can run anywhere from $200 to anywhere in the five figure range. Even if you’re not willing to shell out $1,000, many of the popular gemstones can still be had for an affordable price. Here’s a list of the top 10 most popular stones:

• Diamonds
• Pearls
• Emeralds
• Aquamarine
• Tourmaline
• Opal
• Garnet
• Sapphire   
• Topaz
• Peridot