Tahitians have colloquially been referred to as "black pearls" for a long time, but truly black Tahitian pearls like these are actually quite the rarity. The color of these pearls is indeed natural and they have not been treated in any way. These pearls are highly unusual and great for someone desiring true black pearls.
 
Because there is no real color to them, these pearls have not been given any "letter" grade, but the luster is nearly gem quality, and the surfaces are clean and smooth on the pair, with some very light . 
 
Pictured pearls are shown loose in the size listed on an earring card for size relativity, but price listed includes stud posts and large friction backs in 18K gold of your color choice.  Please contact for alternative setting options including platinum and their pricing.