According to this site it is not a blue tomato but a black or brown one. Some of the pics look like it is blue though.
Current Facts
Darkloom tomatoes, botanically classified as Solanum lycopersicum, are an heirloom variety belonging to the Solanaceae or nightshade family. The pigmented cultivar is a part of a larger grouping of tomato varieties labeled as black or brown tomatoes. These cultivars are categorized under this grouping by the unique characteristic of having an excess amount of chlorophyll or green pigment. Chlorophyll gives the tomato a “brown” or “black” hue when mixed with the dark red tones of the flesh and skin. Black tomatoes are native to Eastern Europe, where pigmented varieties are widely cultivated for their appearance, flavor, and dense nature. Experts estimate there are at least 50 varieties of black tomatoes, including well-known cultivars such as Black Krim, Chocolate Stripes, Black Beauty, Black Prince, or Cherokee Purple. Darkloom tomatoes are a recent variety introduced into the United States through growers in Mexico. The cultivar is still considered rare in American markets and is promoted as a specialty tomato with a complex, balanced flavoring. Darkloom tomatoes can be utilized in fresh and cooked preparations and are favored as slicing tomatoes.
https://specialtyproduce.com/produce...toes_18743.php