Edit in JSFiddle

// ===================================
// Chart1
// ===================================
var data = [
	{
		value: 79,
		color:"#fff"
	},
	{
		value : 21,
        // Draw with background color
		color : "#66ccff" 
	}
];
var ctx = document.getElementById("myChart").getContext("2d");
new Chart(ctx).Doughnut(data,{
	segmentShowStroke : false,
	segmentStrokeColor : "#fff",
	segmentStrokeWidth : 1,
	percentageInnerCutout : 80, // **** Border width
	animation : true,
	animationSteps : 100,
	animationEasing : "easeOutBounce",
	animateRotate : true,
	animateScale : false,
	onAnimationComplete : null
});
// ===================================
// Chart2
// ===================================
var data = [
	{
		value: 62,
		color:"#fff"
	},
	{
		value : 100-62,
		color : "#66ccff"
	}
];
var ctx = document.getElementById("myChart2").getContext("2d");
new Chart(ctx).Doughnut(data,{
	segmentShowStroke : false,
	segmentStrokeColor : "#fff",
	segmentStrokeWidth : 1,
	percentageInnerCutout : 80, // **** Border width
	animation : true,
	animationSteps : 100,
	animationEasing : "easeOutBounce",
	animateRotate : true,
	animateScale : false,
	onAnimationComplete : null
});

<div class="chart">
    <canvas id="myChart" width="200" height="200"></canvas>
    <div class="count">
        <em>79</em>
        <span class="caption">%</span>
    </div>
</div>
<div class="chart" id="chart2">
    <canvas id="myChart2" width="200" height="200"></canvas>
    <div class="count">
        <em>62</em>
        <span class="caption">%</span>
    </div>
</div>

body {
    background: #66ccff;
    padding-top: 20px;
}
.chart {
    position: relative;
    float: left; 
    margin-right: 20px;
}
.chart .count {
    position: absolute;
    border-radius: 50%;
    top: 24px;
    left: 24px;
    height: 152px;
    width: 152px;
}

.chart em, 
.chart span {
    font-family: Arial;
    font-weight: bold;
    width: 100%;
    text-align: center;
}
.chart em {
    display: block;
    font-size: 50px;
    font-style: normal;
    color: #fff;
    line-height: 150px;
}
.chart .caption {
    position: absolute;
    top: 50px;
    left: 40px;
    color: #fff;
}
#chart2 .count {
    background: url(http://startapp.jp/img/refs/jsfiddle_medium_6628140291.jpg) -20px -20px no-repeat;

}
#chart2 .count em {
    color: #fff;
    color: rgba(255, 255, 255, 0.8);
}
/*  ============================
photo credit: <a href="http://www.flickr.com/photos/jiuck/6628140291/">Jiuck</a> via <a href="http://photopin.com">photopin</a> <a href="http://creativecommons.org/licenses/by-nc-sa/2.0/">cc</a>
*/