Naturally colored floors have variations from board to board. This is beautiful and makes it look like real wood. We are referring to woods that are colored this way straight out of the ground with no stain. Each species of wood has different grain; that is where you get to choose your grain and color preference. Each wood will have a different density and wear appeal as well. Some woods are naturally more color variant than others. All naturally colored floors change color after they are freshly cut through oxidation (See: Changing Color blog), but here we are referring to the color blocking or swirling in the actual variation within the floor.
Amendoim has more swirls and can range from blond yellow to dark brown with lots of mineral streaks. Brazilian Cherry is widely known as the most color variant floor. It displays more color blocking, each board a different color from the next. Red oak is often no very color variant unless you choose a more character grade. Color variation is affected by the GRADING process. More similar colors (usually the richer colored heart wood) are selected out and sold at a premium. Less expensive grades often have more color variations and mineral streaks and knots; they call that character grade. If you think all this color variation is not for you, try one of the many STAINS available that are more consistently colored!