This sounds pretty similar to the display on the Pebble Time. It was a color LCD, sometimes marketed as a low power LCD or reflective LCD. For the majority of the time the display didn't use the backlight. They don't seem to be widely manufactured in my attempts to look for them... I should check again!
Sharp’s Memory LCD, I think. Combination of SRAM cells to hold state in each pixel and improved reflexive backing, otherwise normal LCD, so data input can be stopped without losing contents.
Also to parent comment: backlit LCD without backlight looks like brownish tinted frosted glass. Transreflexives look like calculators and never like a paper. There were high contrast monochrome variant in those Memory LCD products and it looked like half silvered mirror, respectively.
