<div class="diamond">
	<img src="http://csssecrets.io/images/adamcatlace.jpg" />
</div>

/**
 * Diamond images — via transforms
 */

.diamond {
	width: 250px;
	height: 250px;
	transform: rotate(45deg);
	overflow: hidden;
	margin: 100px;
}

.diamond img {
	max-width: 100%;
	transform: rotate(-45deg) scale(1.42);
	z-index: -1;
	position: relative;
}