Gem stones may come in a rainbow of colors, but the jewelry industry uses a universally defined system to grade gem stone color. Gem stone color accompanies clarity, cut, and carat weight to make up the 4C's and can greatly affect the aesthetic gem stone price. Many people mistakenly believe that darker is always better, but what they should truly be looking for is brightness and vividness. Use the following tips to accurately evaluate the gem stone color by yourself.
Evaluating Gem Stone Color by Using the GIA or Munsell Color Grading System
Although there are many and equally effective gem stone color grading systems in use today, the GIA or Munsell Color system is a good primer to start with. It utilizes a plastic set made up of 324 color pieces to serve as standard references. If a certain color is found missing from the system, interpolation can be performed to come up with more than 760 additional shades.
The GIA or Munsell system is made ideal for judging the gem stone color because they are built with 3D plastic pieces that resemble faceted gem stones.
Elements of Gem Stone Color
The gem stone color should be judged according to the three main elements:
- Hue This is the first impression we obtain from viewing gem stone colors. It is what makes rubies red, sapphires blue, emeralds green, and amethysts purple. Hues have a natural order and they are red, yellow, green, blue, and lastly purple. Numerous shades can be achieved by mixing together any two of these hues.
- Chroma or Saturation This element refers to the vividness, purity, strength, or intensity of a given gem stone color. Gem stones with low chroma are referred to as weak while those with high levels of saturation are called vivid or strong. Saturation of gem stone color may be classified as the following in ascending order: grayish or brownish, slightly brownish or grayish, very slightly grayish or brownish, moderately strong, strong, and lastly vivid.
- Value or Tone This is what makes you think of red as light or dark red. Gray as well as black and white are referred to as neutral or achromatic gem stone color because they don't possess any hue. Gem stone color with hues are referred to as achromatic colors. GIA uses a numerical system, with its written definitions, to evaluate neutral and achromatic gem stone color alike. For transparent gem stone colore, however, only grades or tones two to eight are considered.
0: colorless or white
1: extremely light
2: very light
4: medium light
6: medium dark
8: very dark
Treatments Used for Changing Colors of Gemstones
When shopping for colored gem stones, another question you should definitely ask and one you couldn't evaluate without a definite honest answer is if the gem stone color is natural or applied. There are several commonly used and accepted gem stone color treatments that are applied to gem stones in order to change their appearance like heat treatment, irradiation, dyeing, and straining.
This is the most commonly utilized and one of the oldest treatments for modifying the gem stone color today. This treatment may use temperature ranging from 100 degrees Celsius to more than 2000 degrees Celsius and improves gem stone color distribution as well as reducing visibility of flaws.
Low or high electromagnetic waves or energy particles are used to change a given gem stone color. Like heat treatment, there is little remaining evidence that could clue a buyer to its use.
With irradiation, certain gem stones have their colors enhanced. Bleached, off-color pearls will obtain a darker tint. Brown or light yellow diamonds can become colored. Light yellow or colorless sapphires may turn yellow to orange, but the change could only last for days. Colorless quartz may turn into smoky quartz. Colorless as well as pale pink and dark blue beryl may become yellow or maxixe-type respectively. Time, light, and heat may, however, cause the color for treated beryl jewelry to fade.
Dyeing and Straining
This is the major term used to refer to various techniques utilizing a foreign and differently colored substance to modify a given gem stone color. A combination of techniques, like dyeing and clarity enhancement for beryl, may be used to improve overall effects. In coating, the application of a second substance is only done on the surface.
Practice makes perfect so browse jewelry shops to familiarize yourself with the various signs that could alert you to the use of applications and treatments on gem stones.