The burning end of a cigar. A bright, white ash indicates tobacco that has received ample magnesium in the soil. Cameroon tobacco typically burns with a bright white ash. A flaky white ash may have had too much magnesium. Cuban tobacco tends to burn with a grayish ash (see photo). A black ash may indicate the tobacco inside was grown in soil lacking proper nutrients.
Fine, handmade cigars are made with long-filler leaves, and the ash on such cigars retains strength even after burning. Some fat cigars can be made to stand upright on their ashes, and can hold ashes of considerable length. (Cigars made with short-filler tobacco tend to have very flaky ashes with little strength.) Resist the urge to tap your ash; it’s better to let it fall when it’s ready, after you see a seam develop, typically around the one-inch-long mark.