1.06 ct. Daylight Fluorescent Mexican Opal
Color: Medium Greenish-Yellow
Clarity: Eye Clean
Origin: Jalisco, Mexico
Cut: Pear Brilliant
Measurements: 9.1 x 6 mm
A new and rather remarkable material. There are plenty of minerals that are fluorescent, that is to say they respond to UV light, either long or short wave. Furthermore, plenty of faceted stones have this response as well - diamonds are often quite fluorescent. But precious few, and essentially none beyond the rarified collector category, are actually daylight fluorescent. That is what you have here, this opal will glow with an intense yellow-green fluorescence in regular old daylight - no special light needed!
Profiled in the Journal of Gemmology a few years back, this material is from a find of hyalite Opal in Jalisco, Mexico. The stone is completely clean and shows a vivid reaction to daylight. Under completely incandescent lighting, the stone is a light stray yellow shade (above middle on both sets of images). Indirect natural light even produces a moderate fluorescence response, but direct sunlight sets the stone aglow and gives you a stone with an almost 'highlighter' yellow color (left images above). As you might expect, exposure to longwave UV light produces an exceptional result - see the above, right images. A rare example of this material in a weight of over 1 carat - given the growth habit of these, larger stones are extremely uncommon. Loupe clean as well. This material will no doubt become the preeminent example of daylight fluorescence in gems.