Jet-black is any black color that is as black as possible given the situation. For example, jet-black hair is hair that is as black as you can get it. Black is a color that absorbs all light. From a digital design perspective, pure black can be considered jet-black as it is as dark as possible. Jet-black is named after the gemstone jet that is a low grade of coal. This is a product of millions of years of high-pressure decomposition of wood. Jet is an extremely dark black and is valued for crafts and jewelry. The following are common types of jet-black with a few similar colors.
Black
#000000
Vantablack
#000100
Jet Black #6
#000200
Black Glaze
#001111
Black Hole
#010203
Black Knight
#010b13
Black Metal
#060606
Jet Black #4
#0a0908
Black Wash
#0c0c0c
Blackout
#0e0702
Smoky Black
#100c08
Glossy Black
#110011
Jet Black #5
#111100
Black Feather
#112222
Kettle Black
#131313
Black Raspberry
#16110d
Cynical Black
#171717
Black Chestnut Oak
#252321
Jet Black #3
#262c2a
Jet Black
#2d2c2f
Jet Black #2
#343434
Notes
The following is a photograph of the mineraloid jet. Jet has a slight brown tinge to it. It is a low grade of coal but is ironically far more valuable than coal as a gemstone. It was popularized by Queen Victoria in the 1850s as she was known for incorporating jet into her mourning dresses. Jet jewelry was considered fashionable through to the 1920s when long strands of jet beads were popular amongst the flapper subculture.