Black Tomatoes are not actually black, just deep, purplish-red.
There are many versions of “Black Tomato” seeds available to the home gardener, some which produce tomatoes which are purplish-brown, others that produce tomatoes that inside seem grey, about the colour of overcooked liver. Neither of which are actually appealing once you see them.
A new Black Tomato was introduced in 2004 in the UK by Sainsbury’s. Sainsbury’s spent 6 years of research and development on the tomatoes. Though said to originate in the Galapagos and South America, the crop is being sourced from Spain. Some think the tomato is sweeter and juicer than red tomatoes. Given that the tomatoes are intended to command a premium price, the better taste may partly be owing to better care being taken in ripening them more fully than the standard red tomatoes.