X - The symbol used on label of confectioner’s sugar. The x represents the degree of fineness, the more x’s,the finer the grade of sugar. The x’s indicate the number of holes per inch on the screens used that form the size of the sugar crystals.
10 X – Confectioner’s (powdered) sugar is sometimes referred to as 10 X sugar. This indicates there were 10 holes per inch in the screens used during processing of the sugar.