Two Color
Two Color How to Evaluate Colored Gemstone Though most people think only diamonds are graded, there is also a set of criteria to evaluate colored gems. These are summarized in a grading report. A ge...
Two Color
How to Evaluate Colored Gemstone
Though most people think only diamonds are graded, there is also a set of criteria to evaluate colored gems. These are summarized in a grading report. A gem's value is primarily based on its color. Here are the basics you need in order to understand a colored stone grading report.
To understand color, remember that there are three primary colors (red, blue, yellow) and three secondary colors, which are the result of mixing primary colors (purple, orange, green). Nature often displays tertiary colors, such as red-orange, yellow-green, or blue-violet, which are a primary color mixed with a secondary color. When a color is mixed with gray, white, or black, we need the (overlapping) definitions of saturation, hue and tints.
Saturation expresses the attribute of perception of gray undermining the depth of color. If a stone were all gray it would be said to have zero saturation. Nature can not produce 100% saturation but if it could, there would 0% gray in the color. As a rule, the higher the saturation percentage is the more expensive the gem will be.
Hue is the actual color perceived whether red, purple, yellow, green etc. In these terms, white, black and gray have no hue. Some hues, like red, pink and blue, are (today) considered being more valuable than others (e.g. yellow or purple). This has and continues to change with fashion, over time and between cultures.
A color mixed with white is called a tint. A tint is lighter and less saturated than its original color. Generally speaking, the less tint, the better the hue, the higher the price. Exceptions are Padparadscha sapphires, Rhodolites and cornflower blue sapphires which are specifically characterized by the combination of hue and tint.
To describe a color technically, one could correctly say, as an example, blue (hue) mixed with 20% gray (saturation) plus a bit of yellow mixed with a lot of white (tint)". Such descriptions are hard to imagine and not very attractive. Therefore color professionals use more illustrative names such as "ivy green", "cornflower blue" or "salmon orange" in connection with attributes like "strong" or "vivid". Because these color names refer to something common and natural they express color in a more accessible way.
For the evaluation of gemstones, saturation, hue and tint are summarized in two criteria called color grade and tone. Color grade describes the strength of the main color compared to other colors visible in the stone. A 100% color grade in blue for example would imply that there are no other colors (like purple or violet) visible in the stone. If there was also no gray in the stone, we would have a 100% saturation with a 100% color grade, but such a stone has never been found. Some varieties (e.g. the Padaparadscha), which are defined by a combination of main colors (e.g. pink and orange), will receive a high color grade from the purity of the combined main colors, meaning the absence of other colors e.g. brown. Generally the rule applies: the purer the color the higher the grade. But grade is nothing without tone.
Any color grade has to be seen in combination with tone. Color tone varies from "very light" to "very dark". It is the amount of black or white mixed into a color. In the extremes, a colored stone could be white (light 5) or black (dark 95) with just a hint of color. Only grade and tone together describe color value sufficiently. A stone might, for example, show a rather pure blue, free of green or violet, but it might be of a very light tone thus the blue is less strong. Or it might, in the opposite, be of such a dark tone, that it appears rather black than blue. Gemstones with high color grades and light-medium to medium-dark tones fetch the highest prices. Grade and tone are expanded upon by applying the terms color zoning, clarity, brilliancy and depth.
Color zoning describes the way in which some stones show colors only in parts or layers. To describe the strength of this common but generally unwanted effect, we use four levels:
1.None: The color is equally distributed
2.Faint: One might see changes in color saturation
3.Gradual: The color weakens in some parts but not abruptly.
4.Visible: Stone has clear color patches or layers.
Other than clarity, which is judged with a 10x lens, color-zoning is described only as far as it is visible to the unaided eye.
The clarity of a stone can range from "Free of Inclusions" to "Excessively Included". Free of inclusions indicated that even under 10x magnification no inclusions become visible. A lightly included stone would show visible inclusions under a 10x magnification but rarely with the unaided eye. Moderately included have inclusions that may be seen with the naked eye. However, they do not dominate the stone. In a heavily included stone, the inclusions are clearly visible and influence the stone's appearance. If a stone is classified excessively included, it may be so flawed as to no longer be durable.
Brilliancy is the estimated maximum light a stone would reflect in one position under a spotlight. High brilliancy is, amongst others, the result of skilled cutting.
Depth is the height of a stone divided by its minimum width. The "ideal" range lies between 60% and 80%. It is mainly determined by the given shape of the rough stone. If the depth percentage is lower than 50%, the stone might be called shallow. A shallow stone with a light tone will find it difficult to maintain saturation. A stone with 90% depth and a dark tone on the other hand might black out.
Brilliancy and depth are joined in the "Cutting Grade" which also includes the general quality and precision of the lapidary's work and the finish of the stone. Here, a dealer will also mention any flaws or other weaknesses regarding the cut.
All quality parameters are then summarized into an overall grade. If you want to keep things simple you just have to look at the overall grade which is described by five levels:
oExcellent: Far above average and flawless. This quality is rarely seen in jewelry and is mostly acquired by collectors or long term investors.
oVery Good: Above average in all criteria with one or two minor flaws.
oGood: Average quality with strengths and weaknesses
oFair: Average quality with one or two obvious flaws
oPoor: Major imperfections
Ninety percent of the stones coming out of an average Sri Lankan mine will fall into the category "poor" and "fair", while only one individual in the whole lot might receive an "excellent".
Whatever gemologists, traders, miners, jewelers or grading reports say, you are the only one authorized to judge beauty. The less you like what everybody else does, the better for your budget! Your first evaluation of a gem will most likely be based on a photo. Remember that today there are many more excellent gem photos than good gems in the market. Always rely on a grading report from a reputable source to get the whole truth about any gem that you are considering purchasing.
About the Author
Edward was born in 1968 in Berlin. His family migrated to Sri Lanka in 1973. He studied biology and international development in London and Berlin. His company, Wild Fish Gems was founded in 2000 as a company specializing in Ceylon gems that have not been treated with radiation, chemicals or heat. He has recently begun sourcing from a broader range of countries across Southeast Asia and Africa. His gemstones are delivered daily to jewelers and gem lovers all over the world.
How Color Printing Conveys The Emotion In Design
Colors convey emotion as well as information. This is a true fact in nature and it is a true fact in color printing as well. We know that bright colors can attract insects to flowers, or people to posters. Red means stop for most of us while red insects usually mean a bad time if animals and people come into contact with them. So as you can see, there are a lot of things that can said through the use of colors. This means you can't take color printing lightly. Designers should not choose random colors, or colors that they favor. Choosing a certain shade for color printing should be a conscious and targeted decision. You must know what colors mean, and what they contribute your color printing design.
Of course this knowledge should be pretty basic to any designer. If you are just starting out with your color designs then here is a little primer on the relationships of colors and the emotion that they carry. For this article, we'll list the major colors that are commonly used today starting of course with the primary ones.
1. Red – When you think of red or when you see something red, you already feel some kind of intense emotion from it. It actually has many meanings, like passion, excitement and Love. Of course, since it is the color of blood, it also has connotations of violence and war. No matter what the meaning though, the emotion it conveys is always intense. It is a color that requires immediate attention and it always invokes something primal in us. So if you want to convey that intense and primal emotion, use red in your color printing.
2. Blue – The color blue and its other shades like light blue or sea blue usually conveys the feeling of calmness and serenity. Since it is the color of a clear sky, or a calm ocean this is hardly surprising. Most of our racial experiences with the color blue has always been pleasant so it is natural that these colors immediately cause those emotions in us. If you message is about calmness and peace, then the cool colors of blue should be used.
3. Yellow – The color of our sun is yellow hence it is the color that conveys the most energy and warmth. Most people integrate this color in their design to convey happiness and joy in their color printing designs. If you ever enjoyed a happy sun drenched day at the beach or the first rays of sun after a winter storm, then you should understand this feeling. So if you want your design vibrant with energy the color yellow is your candidate.
4. Green – The color green is another “cool” color like blue. However it conveys this in a different aspect. Green feels cool to our eyes since it is related to plants and trees. Being among plants and trees is always a refreshing feeling taking away the heat of the sun and cooling bodies down. So people relate the color green with comfort, growth, nature and of course life itself.
5. Orange – The color orange is basically the combination of red and yellow. This also means it is a combination of the emotions of those colors. Orange has the energy of yellow with the increased intensity of red. Of course a lot of people relate this color to the fruit orange, but moreover it is the color of mid-afternoons when the sun is about to set. Orange is usually used as a compliment to yellow and red conveying warmth and contentment.
6. Purple – The color purple has a unique meaning since it is related to history. In ancient and medieval times, the color purple was hard to produce. That meant it was expensive so only royalty usually had the right to wear them Hence, purple has always been about royalty and elegance. Since religion was also part of the high classes it also conveys spirituality and meaning.
7. White – The color white of course for any color printing design means empty space. Though in contrast with other colors it also can convey energy and luminosity.
8. Black – Lastly, we have black. This is basically the absence of color. It usually means the absence of life and the color of the night. Thus it also represents mystery and the unknown. So use this color in more serious and dark messages in your image. It is also the color that can contrast to any kind of color that you match it with.
So remember these colors and their meanings when you make designs for color printing. Use them with purpose and exploit the emotions that they invoke in people. This should help you make designs that have more impact.
About the Author
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