When we look at a gemstone, the first thing that usually catches our attention is the color. Whether it’s an intense sapphire blue or an emerald green, the color really grabs you. But the gemologist looks at color in a different way: it can be one of the most important factors when it comes to identification, rarity and value.
The Three Components of Color
The color of a gemstone is evaluated on the basis of three different components:
- Hue: the color itself
- Tone: the lightness or darkness of color
- Saturation: the intensity or color purity
The interplay of all three components determines how good or bad a gemstone is. The slightest color difference can make a huge difference in value.
Color Determines the Price
Some gemstones are best known for a specific color (for example, a red ruby), while others can occur in a range of shades and colors (such as the different varieties of quartz or topaz). Generally speaking, color is one of the most significant factors determining value because the finest colors are often the rarest. For instance, natural rubies that are pure red with strong saturation are generally considered to be more expensive than those that are reddish-purple, reddish-brown or light in tone. But it’s not just a matter of the rarity of a particular color. Other important factors include the evenness of color, brightness and lack of dark color in the stone.
Color and Modern Technology
In the laboratory and jewelry stores, gems are enhanced by heat treatment, irradiation, diffusion, oiling and other treatment processes. These treatment processes are designed to produce a more visually pleasing color. However, because treatments affect the color and durability of some gems, they also impact the market value.
Gemologists know what the color of a gemstone should be like when it occurs naturally. They also are familiar with various colors that may have been produced by enhancement processes. For this reason, color is one of the most important properties to keep in mind when examining gemstones and trying to determine whether it is natural or enhanced.
Identifying a Gemstone by Color
Although color is an important property to keep in mind when identifying a gemstone, it is not usually the only one. Many gemstones share a single color and gemstones of the same species can be a range of different colors.
In addition to color, gemologists rely on optical properties and visual examinations to identify a gemstone. Advanced technology like the gem microscope and other lab instrumentation can also provide important information during the identification process.
Summary
Color gives gems their beauty and individuality. From a gemologists perspective, however, color is a source of information. Knowing how to interpret color is part of what every gemologist is taught in order to understand and use the gemological properties. If you work with gemstones or jewelry, it is important for you to know all you can about identifying gemstones.
