Rock #5258
Light refraction causes electric blue agate

I have never seen anything quite like this before from The Carver Agate Field.  The presence of the sagenitic growth seen in this specimen no doubt is largely responsible for the electric blue color.  While the sagenitic golden material obviously is not blue, I believe that it captures certain wave lengths of light that enter the stone, while in this case leaving the blue light wave lengths to refract back out of the stone and make it appear deep blue. 

The refraction of light by the internal characteristics of a stone is not unusual—think of diamonds and opals.  On page 27 of his book Gemstones of the World, 1977, Walter Schumann explains as follows: “color is produced by light;  light is electromagnetic vibrations at certain wave lengths.  This visible light falls into six parts, each of a particular color (the spectral colors: red, orange, yellow, green, blue,  violet).  The mixture produces white light.  If, however, a certain wave length is absorbed, the remaining mixture is a color, but not white.  If only certain wave lengths are absorbed, the stone will have the color resulting from the remaining spectral mixture.”   

Here the stone’s entire interior, just inside the rind, captures most of the light spectrum, but allows the blue light portion of the spectrum to vigorously reflect back toward your eye as blue.  It is also worth noting that the type of lighting in which the stone is observed or photographed will greatly influence the colors that you see because different types of lighting contain varied wave lengths within the color spectrum.  I have also observed from this particular stone that the blue is more vivid when photographed on a heavily overcast/foggy day and less blue in bright sunlight or with strong artificial lighting.

Rock #5276
Frog Mountain Agate with pretty blue center
A large cabochon destined for an eye catching pendant

Rock #5280
Blue/yellow/black contrast makes for a pretty cab

Rock #5282
Blue fortification agate inclusion sets off the flower garden agate seen on the left

Rock #5265
Blue inclusion creates an outstanding jasp/agate—with a face looking out at you!

Rock #5255A
Imagine a far-off world with blue oceans and brown land masses

Rock #5272
Another example of blue light refraction which makes an otherwise bland stone “pop”

Rock #5283A
Blue refraction sets off the brown lava shards which were captured
inside the nodule which I slabbed and turned into an oddball cab

Rock #5288
Another blue agate cab containing a lava inclusion