When it comes to gemstones, diamonds are easily the global favorite. You will find them in necklaces that women pass down through generations, in the all-important engagement rings of hopeful couples, and in many priceless bracelets everywhere. They even have their place in demanding industries that deal with a lot of glass, sturdy polymers and tough metals, since their amazing hardness allows them to cut through basically anything.
However, this immense popularity should not be allowed to overshadow other gemstones out there. In fact, even though diamonds come in several different colors, that is barely a speck of the multitude of colored gemstones out there. If you check out a directory like this one, you can get an idea of the many different varieties there are. So when you come across a colored gemstone, how can you figure out what you are dealing with?
Understand the three basic factors
The three major items in grading the quality of colored gems are the saturation, the color, and the hue of the stone. Let’s take a look at each.
Saturation refers to the interplay of color and grayness. When the inherent “depth” of a given color is dulled down by the presence of gray, we say that the stone lacks saturation.
In other words, a 100% saturated gem would be entirely free of any grayness throughout. This never really occurs in nature; therefore, the closer a gemstone is to this ideal saturation level the more valuable and expensive it will be.
The value and price are further augmented by the accompanying metals and the processing and shaping of the stone. A chart of cuts can give you a comprehensive idea of the various gemstones made appropriate for jewelry.
Colors are classified as primary (yellow, red, and blue) and secondary (orange, purple, and green). This is the typical setup that you see on the color wheel. However, in the natural world, there is a wide prevalence of tertiary colors as well.
A tertiary color is made by overlapping a primary and secondary color. For example, if you mix the primary blue with the secondary green (which in itself is already a mix of blue and yellow), you will typically end up with some shade of turquoise.
Of course, a color can also mix with white, black, or gray. In those cases, we reach for the ideas of saturation and hue, as well as tint.
The hue is the actual “color our eyes perceive”, in other words, the pigment – those primary and secondary ones from earlier. In that sense, white, black, and gray are technically “colors” but they have no “hue”. Believe it or not, this idea has been a philosophical battleground for ages, and you can see that in this comprehensive historical overview: http://www.huevaluechroma.com/071.php
Over the years, some hues grow more popular, more appreciated, and therefore costlier than others. In our day, blue, pink, and red are considered more desirable than yellow or purple, but these attitudes are just a fashion trend. Moreover, they are culturally conditioned, so people from different countries and traditions will have different preferences of gemstone colors.
As an honorary factor, we briefly mentioned tint. A gemstone is said to be tinted if its inherent color is mixed in with some white, making it lighter than usual. By the above logic, tinted stones are less saturated than their “original”, “default” counterparts; and therefore they are less appreciated. The more tinted the gem, the less valuable it will be, in turn making them more affordable.
There are three prestigious exceptions to this rule, where the gemstone’s high value is possible exactly because of the unique hue/ tint ratio. These are the cornflower blue sapphire, the Rhodolite (a sub-type of garnet), and the esteemed Padparadscha sapphire (the rarest, delicate, pink-orange corundum mineral whose name is derived from the color of the lotus).
More can be learned about a colored gemstone, if you look at things like tone, color grade, color zoning, depth, brilliancy, and clarity. These concepts are more advanced, and out of the scope of this crash course, but stick to the basics here and you can find your perfect gemstone for sure.