.icon-container {
background-color: #BBB;
font-size:72px;
float: left;
}
.icon {
color: #FFF;
margin: 3px;
}
.fb-gradient:hover {
background-image: -webkit-gradient( linear, left top, right bottom, color-stop(0, #3b5998), color-stop(1, #fff));
background-image: gradient( linear, left top, right bottom, color-stop(0, #3b5998), color-stop(1, #fff) );
color:transparent;
-webkit-background-clip: text;
background-clip: text;
}
.instagram:hover {
background: #f09433;
background: -moz-linear-gradient(45deg, #f09433 0%, #e6683c 25%, #dc2743 50%, #cc2366 75%, #bc1888 100%);
background: -webkit-linear-gradient(45deg, #f09433 0%,#e6683c 25%,#dc2743 50%,#cc2366 75%,#bc1888 100%);
background: linear-gradient(45deg, #f09433 0%,#e6683c 25%,#dc2743 50%,#cc2366 75%,#bc1888 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#f09433', endColorstr='#bc1888',GradientType=1 );
color:transparent;
-webkit-background-clip: text;
background-clip: text;
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="icon-container">
<i class="fa fa-facebook icon fb-gradient" aria-hidden="true"></i>
<i class="fa fa-instagram icon instagram" aria-hidden="true"></i>
</div>