Some tile manufacturers use a stone coating, but then paint over the top. The chip coverage is often poor and the paint tends to change colour over a shorter period of time.
By using natural stones, Decra tiles will not change colour. Also the chip coverage and the bonding of the chip is generally to a much higher standard when compared to other metal tiles. This is important particularly over time because it ensures the basecoats and substrates are protected from weather damage and thus ensuring that the product looks better for much much longer.