Black ink tattoos are those tattoos which are made only with black ink. There are plenty of tattoos which are made with only black color, like Celtics tattoos, tribal tattoos, Japanese tattoos and symbols tattoos. In fact, you can make anything with this color. There is no restriction of colors in other tattoos as well, but it depends upon the choice of the customer that which color he wants to choose for his tattoo. If he likes to have just one color on his tattoo then, he would engrave his tattoo with black color. If he likes to have more than one color, then he can add some other colors as well with the black color.
You can also take some advice from your tattooist in this matter as well, because they are normally in a better position to guide you if a black tattoo would suit you most or a colored tattoo. The black tattoo has some advantages on colored tattoos. A statement written in black ink might have a better impression than a colored statement. Similarly, the black inked tattoo will cost you less as compared to the colored tattoo.
There are some reports which say that actually at first the tattooing was started with just the black ink. But, later, with the passage of time, the trend got changed and other colors started replacing black. The black, however, stands still on its place and its importance has not been ended. It seems like the use of black inked tattoos will never be ended.