KOZIBE effect—need I say more?
I am completely smitten with this stone, and I suspect you will be too. Presented in its original French antique, hallmarked setting, this exquisite 2.58 carat old mine brilliant cut diamond (L color, SI2) is set in rich, buttery 18 karat yellow gold.
What makes her truly captivating is how beautifully she faces up—bright, lively, and far whiter than her color grade would suggest. That magic is thanks to the Kozibe effect, a hallmark of old-cut diamonds, where the culet reflects through the crown facets, creating a mesmerizing, almost halo-like glow within the stone. It’s a detail collectors quietly obsess over… and once you see it, you can’t unsee it.
And then there’s the setting. Take a moment with her—you’ll notice the delicate, hand-executed details that speak to a bygone era. A timeless solitaire at first glance, yet infused with an early Victorian sensibility, where every line and flourish feels thoughtfully composed. The mounting cradles the diamond with understated elegance while offering that unmistakable, one-of-a-kind antique character—complete with original French hallmarks.
Pieces like this are becoming increasingly difficult to source, especially with this level of presence and authenticity. If you’ve been waiting for something truly special—this may be the one to act on.
Antique French 2.58ct Old Mine Brilliant Cut with Kozibe Effect 18k 
C.1850-1890
GIA certified
2.58ct 
Old Mine Brilliant (with Kzobie) 
L ( face up GH)
Si2 
French hallmarks
3.75g 
Size 4.5 (sizable)