November 6, 2017 
 
Ali Brownrigg

9 Things to Know About Gemstones

The world of gemstones is a fascinating one. For example, did you know that sapphire and ruby are the same mineral, just different colors, or that peridot is formed during volcanic eruptions?.

No? Well, read on for more fascinating gemstone facts.

Gemstones by Color
Fancy Sapphire and Diamond Halo Statement Necklace in 18k White Gold
Fancy Sapphire and Diamond Halo Statement Necklace in 18k White Gold

Color is hands down the most important thing to consider when purchasing a gemstone. The color saturation, depth of tone, and hue are the factors that determine the gemstone’s value.

While the range of gemstone types and colors is vast, there are three key components to keep in mind when considering a jewelry purchase: hue, tone, and saturation.

Hue Are You?
Emerald-Cut Sapphire and Diamond Halo Ring in 18k White Gold
Emerald-Cut Sapphire and Diamond Halo Ring in 18k White Gold

A gemstone’s hue is another way of describing its color. Some hues are more valued than others. For example, the ideal sapphire is in the velvety-blue to violet-blue range. A sapphire that is lighter or darker in color is considered less valuable. GIA has developed a color grading system that includes 31 different hues ranging from red to brown, with gradations such as slightly yellowish green and very strongly greenish blue, in the mix.

What about Tone?

A gemstone’s depth of tone is an important factor that influences a gemstones hue. Tone refers to the lightness or darkness of a gemstone, so following our example of a sapphire above, one that has a medium to medium-dark tone is more highly prized than one with an extremely light or extremely dark tone.

A Note on Saturation
Sunburst Turquoise and White Sapphire Pendant in 14k Yellow Gold
Sunburst Turquoise and White Sapphire Pendant in 14k Yellow Gold
Getting Clarity

Almost all gemstones, even highly prized ones, contain inclusions. Flawless gemstones are very rare and very expensive. Most industry experts agree that inclusions are what give colored gemstones their unique personality. Some gems, like emeralds, are typically treated with colorless oil, wax or resin to minimize inclusions that reach the surface of the gemstone.

What is the Mohs Scale?

The relative hardness of all gemstones is gauged using the Mohs scale. Created in 1812 by a German mineralogist, the scale helps determines what a mineral is by testing its scratch resistance. A diamond, which is extremely hard, is a 10 on the Mohs scale, while talc, which is extremely soft, is a 1. However, keep in mind that Mohs is an ordinal scale, which means that while diamond is a 10 and corundum (sapphire and ruby) is a 9, diamonds are actually 4 times as hard as corundum.

The Importance of Cut
Citrine and Madeira Citrine Drop Earrings in Sterling Silver
Citrine and Madeira Citrine Drop Earrings in Sterling Silver

Unlike diamonds, there is no ideal cut for colored gemstones to maximum brilliance. However, a well-cut gemstone is one that produces the most even color, exposes the fewest inclusions, and enhances the gem’s color.

When a gemstone is cut correctly, the color is rich and saturated because the light is properly reflected. When cut too shallow, the stone looks lighter in color because the light escapes, rather than reflects off the facets. A stone that has been cut too deep appears dark because the light is lost within the stone, rather than returned to the eye.

Does Size Matter?

Because all gemstones have different densities, two gems that are the same size may have different weights. For example, rubies are denser than diamonds, so a 1 Carat ruby looks smaller than a 1 Carat diamond. So, the carat weight of a gemstone is not really an accurate way to gauge the size of a gemstone. Instead, look for the diameter of the gemstone when viewed from above—a measurement we include in all the gemstone jewelry we sell.

Understanding Enhancements

Nearly all gemstones today, including the ones we sell, have been treated to enhance their color and/or clarity. The most common methods of treatment are heating (aquamarine, citrine, amethyst, sapphire, ruby, and tanzanite), bleaching (pearls), and irradiation (blue topaz).

Gemstones that have gorgeous color and clarity but have not been treated command extravagant prices. Most enhancement treatments are permanent, but some require special care.

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