I learned a trick during the rigging of my Roberts monitor. I used five mil monofilament, both black and white. I used black for the stays and white for other things (signal halyards and antenna wires (I colored the antenna with a brown magic marker after rigging it). Anyway, I could not see either the black or white while doing the rigging- it got lost in the clutter of the workbench. What I found works, is to cut two panels from black and from white foamcore. I propped up the white piece as a background while I was rigging with the black thread, and the using the black piece as I rigged with the white stuff. At times it was inevitable that the thread would tend to disappear against parts of the ship, but I was still able to complete the rigging by moving the thread till I regained sight of it against the background panel.
The result was rigging that was barely perceptible afterwards, which I feel is desireable. Use of too high a contrast, either because of color or of size, looks bad, to me, on small scale ships. Ordinarily, when using larger threads on larger scales, I use shades of gray or offwhite. Steel rigging on modern ships is not a stark black, and on fiber lines the fiber is usually not pure white. But once a line falls below a certain size (angular) with respect to your eye resolution, your eye and brain only perceive the contrast, not the color, so I find five mil stuff does work in black and white, the only colors I have found to buy in that diameter.
BTW, I am 79, and just had cataract surgery, during building of that model. Rigging is sure easier now!