1.28 ct. Daylight Fluorescent Mexican Opal
Posted: Wed Apr 22, 2020 5:00 pm
From my friend, Brad The Gem Trader, here's a beautiful example of rare daylight fluorescent hyalite opal, in a rare size being over one carat, and faceted to boot, that I thought y'all would enjoy seeing. If I could I'd be buying it, but c'est la vie. 
1.28 ct. Daylight Fluorescent Mexican Opal
1.28 ct. Daylight Fluorescent Mexican Opal
* Color: Medium Greenish-Yellow
* Clarity: Eye Clean
* Origin: Jalisco, Mexico
* Cut: Oval Brilliant
* Treatments: None
* Measurements: 9.2 x 7.1 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 bright 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 moderate reaction to daylight and a vivid one to longwave UV. Natural light even produces a moderate fluorescence response and gives the stone a fine bright yellow-green color - images above, left of each set. 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.
$350 / carat - $448 total
https://www.thegemtrader.com/106-ct-day ... are-gems-2