Well maybe that's a stretch. But it certainly is safe to say that MANY black rugs are actually not black at all.
Take for example the image of our Rug Rag office carpet shown below. It's an Isfahan Design Indian made carpet with 3 ply textile wool in a 14/70 quality, or approximately 220 kpsi. It has a lot of colors, and is certainly an exquisite rug. It has a black border and black field:
Well, here's the same rug in a different area of the field seen below. You may see what we're getting at here about the no such thing as black. It's fairly common that when wool is dyed for weaving, the "color" black is often just a heavily concentrated and saturated pigment of blue or red. Take a guess which dye was used below to color wool...
Although the rug looks black from a distance, under very strong direct
sunlight, we see the true colors of this carpet appear in photographs above and below. While not all rugs use this heavy saturated blue or red, extreme detail of this rug below reveals the true nature of this particular "black" origin... A Very, Very Deep Red.