Grading Precious Gemstones
Gemstone Color Description
The color description system that we use is not so different from a number of other systems, but we believe in many cases it is more flexible.
Do you know how pure Red looks? What if red has components of orange or violet? How about pure Blue? What if blue has components of green or purple?
We recommend that if you are serious about learning color, you get good quality color standards that designate hue, tone and saturation.
Describing Colors in Gemstones
The core of any color description system is obviously the "hue", which is designated by a letter such as Red, Blue, Green, etc.
Another hue designation written as a prefix acts as a modifier. As an example, OR would mean "Orangy Red"
Then if we prefix our OR with another modifier such as a [-] or [+], we can relate the strength of the secondary hue. Examples might be:
- +OR = "strongly ornangy red"
- -OR = "slightly orangy red".
- +VR = "strongly violet red"
- -GB = "slightly greenish blue"
And, quite naturally, the position of the secondary component letter designation determines which is the primary hue and which is secondary.
Example: GB would mean "greenish blue", while BG would mean "bluish green".
Some stones will have such a pure hue that the only designation required is the letter, such as the spinel pictured above that could simply be described as R.
When the color description is combined with saturation, tone and grading designation, the resulting system can be very powerful.
It is an easily understood system that can be written in "long hand"
or "shorthand" and be quickly communicated.