Gemstone Jewelry Guide

The jewelry industry recognizes the highest quality gemstones by purity of their hue, the depth of tone, and color saturation. The best values are colors that include slight traces of other hues, are not too light or too dark, and have a lot of saturated color

The beautiful color of a gemstone is its most defining characteristic and many jewelers consider it to be the most important evaluation criterion. When deciding upon a gemstone's color, pay attention to its hue, tone, and saturation

Hue

"Hue" refers to the slight variation from the stone's primary color. For example, sapphires can range in hue from slightly purplish-blue to slightly greenish-blue, pink sapphires can range from pink to slightly purplish-pink, and rubies can range from slightly orangish-red to slightly purplish-red

Tone

"Tone" represents the depth of color, ranging from colorless to black. Gemstone tone is described as "light," "medium-light," "medium," "medium-dark," and "dark." The most sought-after tones fall within the medium-light to medium-dark range

Saturation

Saturation, or color purity, refers to the degree to which the gem is free from brown or gray hues. The most desirable gemstones, which show little gray or brown, are often described as having "vivid" or "strong" color saturation.

Buyer's Tip

In a gemstone with more saturated color, the best cut may be more shallow than average, permitting more light to penetrate the gemstone, while in a less saturated gem, the color may benefit from a deeper cut.

Clarity

Identifying marks

Because gemstones form under unique circumstances, each individual gemstone is comprised of a combination of trace minerals, which create a unique set of identifying marks or inclusions. Inclusions will not necessarily detract from the beauty or desirability of a colored gemstone.

What to look for

When considering a colored gemstone's clarity, you should measure your expectations against the standard for that variety of gemstone. Some varieties of colored gemstones, such as aquamarine, blue topaz, and citrine, have naturally fewer inclusions while other gemstones, such as emerald and ruby, tend to have a higher rate of acceptable inclusions

Clarity is an important factor in comparing quality colored gemstones. Even opaque opals can have milky inclusions that will affect their iridescence and color play. In general, the best values are available in gemstones that are moderately included. Exceptional gemstones with few or no inclusions are available, but they can command extravagant prices.

Cut

Colored gemstones are generally cut to maximize the beauty of their color. To recognize quality in the cut of a gemstone, there are several points to consider.

What to look for

A good cut showcases the gemstone's color, diminishes its inclusions, and exhibits good overall symmetry and proportion. Because gemstone color can vary, there are no hard geometrical standards when it comes to maximizing brilliance or color. Gemstones, especially rarer ones, are sometimes cut for size without regard for their color. For example, when corundum varieties such as sapphire and ruby are cut for maximum weight rather than beauty, they may display banded colors or streaks

Gemstone cut

Look at the gemstone in the setting and ensure that all the facets are symmetrical. An asymmetrically-cut crown indicates a gemstone of low-quality. In all cases, a well-cut gemstone is symmetrical and reflects light evenly across the surface and the polish is smooth, without any nicks or scratches.

Buyer's Tip

Like diamonds, fine quality colored gems usually have a table, crown, girdle, pavilion, and culet. Iridescent opals are one exception, and most often have a rounded cabochon cut.

Size

Different densities

The carat weight of a gemstone does not necessarily allow you to accurately envision its size. Different gemstones have different densities (mass per unit volume), so two gems that appear to be the same size may actually have very different weights. For example, a ruby is more dense than a diamond, so a 1-carat ruby will look smaller than a 1-carat diamond.

Buyer's Tip

Always request the dimensions of a gemstone to ensure that the majority of the gemstone weight will be visible when placed in the setting.

Enhancements

Unpolished gemstones are typically very rough. Gemstones straight from the mine might be mistaken for pebbles or gravel.

Part of the process

Almost every colored gemstone you will come across has been heat-treated. It is a common practice around the globe and has been going on for centuries. Heating completes a process nature started, and is used to enhance the colors of a gemstone.

The jewelry industry recognizes heating as acceptable and expected and part of the standard polishing and finishing process for many gemstone varieties. The heating of gemstones is a practice accepted by the American Gem Trade Association (AGTA).

Buyer's Tip

Nearly all gemstones available on the open market have been enhanced. Those that have not been enhanced are very rare and command extravagant prices. Before buying a gemstone that has not been enhanced, ask to see a grading report, preferably one from a well-known gemstone grading lab (like the AGTA). The grading report should state that the gem shows no indication of enhancement by heat

Care

After removing your gemstone jewelry, wipe it with a soft cloth to remove dirt and other residues.

In general, all you need to clean your gemstones is warm, soapy water and a very soft brush. A soft toothbrush and mild dishwashing liquid does a good job. Remove your jewelry, let it soak in the soapy water for about 20 minutes, and then gently brush it and rinse thoroughly. Be careful not to scratch the metal of your setting.

Home ultrasonic cleaners are not recommended for all of your colored gemstones. Ruby and sapphire are typically safe to clean in an ultrasonic cleaner but other gemstones are not. Because of their porous composition, opals should never be cleaned in an ultrasonic cleaner. Similarly, emeralds should always be cleaned by hand.

Storing gemstones

Store your gemstone jewelry in a lined case or a soft cloth, so the gems do not touch each other or parts of other jewelry. Gemstones are harder than gold, silver, or platinum and can scratch the surfaces of your other fine jewelry if they are not kept separate.

Wearing gemstone jewelry

While it's true that gemstones such as ruby and sapphire are second only to diamond on the hardness scale, it is not a measurement of their indestructibility. It means that these gemstones are able to resist scratching almost as well as diamond. Abrasive surfaces, harsh chemicals, and sharp blows can damage even the toughest gem. Your gemstone jewelry should be the last thing you put on when getting dressed and the first thing you take off at the end of the night. Store it carefully and it will be enjoyed for generations.