Mace comes from nutmeg. The lacy aril is removed by hand from the outer shell of the nutmeg and then dried, becoming yellowish-brown mace. Mace is sold in whole pieces called blades or in the more commonly-found ground form. The color can often help you determine its origin. Orange-yellow blades most likely come from Grenada, while orange-red blades tend to be from Indonesia.
Mace has a flavor described as a combination of cinnamon and pepper, a more pungent version of nutmeg. It is used in cakes, puddings, custards, desserts, cheese dishes, souffles, sauces, soups, poultry, and fish. It especially complements dishes with cherries or chocolate.
Unlike most spices, ground mace has a longer shelf-life when stored properly in a tightly-sealed jar or container in a cool, dark place. One teaspoon ground mace equals 1 tablespoon mace blades. Nutmeg may be substituted for mace in a pinch and vice versa, but obviously the flavor of the end result will be affected as with any substitution.