2,061. Defining Some of the Colors

Hilchos Issurei Biah 5:9

If the color of a stain matches any of the four aforementioned shades, or if it’s deeper than them, then the woman is ritually unclean; if it’s lighter than these shades, then she is ritually clean. Pursuant to this, if a black stain is darker than dried ink, the woman is unclean, while if it’s lighter – such as if it’s the color of a black olive, tar or a raven – then she is clean. The same rule applies to the other three colors.

Hilchos Issurei Biah 5:10

“Like diluted wine” means like one part fresh, undiluted wine like that of the Sharon in Israel mixed with two parts water. If a stain is darker or lighter than this, then the woman is ritually clean; in order to be rendered unclean, a stain must be the exact color of this mixture. A woman’s word is accepted if she says that she had a stain of a certain shade but she lost the cloth. An expert then decides whether this makes her clean or unclean.