What makes our diamonds different colors?

In 1817 French mineralogist and museum director, R.J. Hauy said “Gems are the flowers of the mineral kingdom and the fancy colored diamonds are the orchids”.  Looking at our yellow and brown rough diamonds here at the Crater of Diamonds State Park, it is possible to see what he meant.  All diamonds have some color to them, but it is about 1 in 10,000 diamonds that have enough color to be called “fancy”.  Here at the Crater a majority of our diamonds are white, with yellow next, and brown coming in third.  Black diamonds are said to have been found only one or two times in the last 104 years that the Crater has been mined. 

A pure carbon diamond with no impurities would be perfectly transparent and colorless.  Color plays a large part in the grading of the individual diamonds to assess their worth or grade.  In order to grade the diamonds, over the years a grading scale has developed that is now used by internationally recognized laboratories.  This scale ranges from D, colorless to Z, light yellow.  Each of the grades in the scale has a masterstone which has been chosen because it represents the very least amount of color within that grade.  Individual stones are then placed within a grade based on their color in comparison to the masterstone.  A full set of masterstones contains 296 diamonds.  While most diamonds are graded by people, both normal and fancy diamonds can now be graded using a Gran Colorimeter manufactured by Sarin Technologies. 

In the nearly white or colorless diamonds, they are classed into two main types:  Type 1 has nitrogen as an impurity and Type 2 has no measurable nitrogen, but has deformities in the diamond’s crystal structure that give them color.  The normal color range for the Type 1 diamonds is within a range from pale yellow to brown.  In order to grade the diamonds, over the years a grading scale has developed that is now used by internationally recognized laboratories. 

The Strawn-Wagner diamond found here at the Crater has a color rating of “D”, and thus is almost perfectly colorless, with a unique icy look.  Therefore, that diamond is worth more money than a similar diamond with a color lower on the scale.  Oddly enough, diamonds toward the D end of the scale are often called “high-color” diamonds and diamonds in the lower part of the scale near Z are known as “low-color” diamonds.  In this usage the high refers to the relative desirability or worth, rather than the color intensity. 

“Fancy diamonds” or those that fall outside of the normal  D to Z color range, have their own grading system.  The 27 color hues encompass the full range of colors, from red around the color wheel to purple.  Each of these hues is then divided into 9 other grades, ranging from “faint” to “fancy dark”.  Many of the Crater’s yellow and brown diamonds would fall within this grading system.  The bright “canary” yellow diamonds, sometimes found at the Crater, are extremely rare and sought after because the color is so intense.  Other fancy diamonds with deep hues, like the deep blue Hope Diamond, are some of the most valuable diamonds ever found.  The colors of the fancy diamonds can be caused by impurities of other elements besides nitrogen.  Manganese gives a pinkish  to ruby red tone, boron often results in a blue color, and brown diamonds often result from uranium radiation over millions of years.  So, whether the diamond you find at the Crater is white or yellow or brown, it is still an extra special diamond because it was found at America’s only diamond mine.

Search area last plowed:  June 18, 2009

Diamond finds for July 6 - July 12, 2009 (100 pts. = 1 carat):

July 6 - Vicki Blalock, Mustang, OK, 10 pt. white; Eric Harger, Hartford, AR, 12 pt. white; Cecillee Duncan, Fayetteville, AR, 20 pt. white

July 7 - No diamonds

July 8 - David Wade, Loveland, OH, 49 pt. brown

July 9 - Dannett Stone, Grayson, KY, 9pt. white;  Kenneth Shoemaker, Murfreesboro, AR, 7 pt. white; Robert and Anna Ford, Waldron, AR, 64 pt. brown, 96 pt. white

July 10 - Tanner White, Fort Worth, TX, 8 pt. white;  Denis Tyrrell, Murfreesboro, AR, 1 pt. white, 1 pt. white, 2 pt. white, 2 pt. yellow, 2 pt. yellow, 2 pt, white, 2 pt. white, 4 pt. white, 4 pt. white, 5 pt. white, 5 pt. white, 6 pt. white, 6 pt. white, 6 pt. brown, 7 pt. brown, 7 pt. white, 8 pt. white, 8 pt. white, 9 pt. white, 10 pt. white, 10 pt. yellow, 10 pt. white, 11 pt. brown, 12 pt. brown, 13 pt. white, 13 pt. white, 16 pt. white, 18 pt. yellow, 19 pt. white, 20 pt. brown, 21 pt. white, 29 pt. white, 30 pt. white, 31 pt. yellow, 32 pt. brown, 34 pt. brown, 35 pt. white, 55 pt. white; Rita and Joe Walker, Hartford, AR, 14 pt. white

July 11 - Tammy Sowells, Mt. Burg, AR, 10 pt. brown, 3 pt. white; Sarah Feddersen, Burleson, TX, 14 pt. white; Glenn Worthington, Springdale AR, 2 pt. white, 2 pt. brown, 3 pt. white, 5 pt. yellow, 6 pt. white, 13 pt. brown

July 12 - Denis Tyrrell, Murfreesboro, AR, 9 pt. yellow, 9 pt. yellow