That's a really interesting thought! But it's not the same reason. Lymph would obviously be more affected by tatoo ink, as macrophages engulf the metal in the tattoo ink, and then return to the lymph.

Really interesting to learn that about lymph. very much appreciate the additional info, but no, the high bilirubin making plasma look dark yellow, greenish or kinda black (called "icteric") is only from bilirubin.

Also it's not really black, just a very very dark greenish yellow.

Additionally, some medications can make the plasma look kind of green.

Clinical scientist here, I analyze bilirubin (and other things) in blood.

An abnormally high bilirubin makes people look yellow, or "jaundiced." Also, high concentrations make your blood plasma (the liquid part of your blood) look much darker than normal. (Most plasma is light yellow, similar to urine). But a high bilirubin plasma will be dark yellow to green to black! And it stains the glass test tubes with its color. Interesting and not really something I knew till I started my career. Thought I could share