In your ketucari's genotype, sable is denoted by the letters "nSb" (heterozygous) or "SbSb" (homozygous).
In its heterozygous form, sable has a pass rate of 55%. Homozygous sable has a 80% pass rate.
Sable must be a darker color of your chosen base, with a minor deviation in hue. It can also be a fully desaturated color of the base, as long as it is darker. Sable may be pure black. Be careful not to make your ketucari look like a pseudo-charcoal using this marking, as it will be rejected.
These colors would be acceptable for this base color. They are either a darker version of the base, or a darker and desaturated version of the base. The last color on the right shows a minor deviation in hue, and is slightly more yellow than the base itself. Notice that this small change is not overbearing.
These colors would be unacceptable for sable. They are either lighter than the base coat or have too drastic a hue shift.