Midnight is the transition time period from one day to the next: the moment when the date changes. In ancient Roman timekeeping, midnight was halfway between sunset and sunrise, varying according to the seasons. Source: Wikipedia. Shui Long Midnight continues a colourway first started with the release of Starry Night Midnight (released in a 100% cotton and a bamboo/cotton blend).
The original ‘Midnight’ was a Dyed Grad, that has since been renamed to Midnite. I think it was renamed so as to avoid confusion regarding colourways between the jacquard woven range (black warp and ecru weft) and the dyed gradations on linen (dyed white or natural linen).