OpalThis "Round Cabochon" cut gem has a beautiful colorless interior in transmitted light, but in reflected light it shows the highly desirable and seldom seen COLOR FLASH or "Contra Luz" effect with a beautiful rainbow like array of color! The color flash is best seen in sunlight or with a strong flashlight against a black background, and this stone was photographed under a strong light to better illustrate the effect. When strongly lit, this stone shows

This specimen is from a find from the mid-1990s at the famed Uchucchacua Mine in Peru

It's not likely we will see these again

It is aspecifically an amorphous (often colorless) form of Opal that is found in spherical aggregates

colorless Hyalite Opal (“Blood Vessel Opal”) which are included with small amounts of iron oxide to create the thin reddish-orange “blood vessel”-like lines that not only give the piece color

the miner in Bolivia who found the specimens was referring to them as “dientes” (Spanish for teeth)

This mine is probably best known for its amazing pink Rhodochrosite specimens

bi-colored modified crystals with rich purple "cores" and light greenish-blue exteriors measuring up to 1

Isolated crystals of Vivianite on matrix from Tomokoni are notably hard to find

and only a few of them are seen on the market coming out of old collections

as we most often see what is called a “fish tail” habit with a somewhat narrow / slender appearance

and this particular piece was one that I held back when I first purchased these specimens in anticipation that more were on the way

Item # BVOPAL293