Because of the range of color differences between white cment and various aggregates, the choice of aggregate can have considerable effect on the color of white concrete. Aggregates used in white concrete should meet requirements of ASTM C33 or C330. They should be particularly clean and free from clay, mineral dust, organic impurities and particles containing iron oxide. Unsuitable aggregates not only can affect the strength of the concrete but can influence its final color. The type of sand greatly affects the color of white concrete and offers additional opportunity to vary the color effect. Fine sand particles act as a pigment to color the cement paste. In many cases, the fines prepared from crushed coarse aggregate are used instead of pigments. If maximum whiteness is desired, a natural or manufactured white or light yellow sand should be used. Most naturally colored sands lack required whiteness. Manufactured aggregates usually consist of crushed limestone or quartzite sands. Among the most popular decorative aggregates are natural materials such as quartz, marble, granite and gravel, and manufactured materials such as glass and ceramic. Clear quartz is used widely to provide a sparkling surface to complement the color created by use of pigmented concrete. It many be used in combination with colored aggregates to emphasize the color of the matrix. White quartz ranges form a translucent white to a deep milky white. Rose quartz give finishes ranging form a delicate pink to a warm rose color. Among all the aggregates, marble probably offers the widest selection of colors, including green, yellow, red, pink, blue, grey, white, and black. In some areas, blue and yellow marble aggregates are available in pastel hues.