How to edit widget code to add unique class name to each div?

Code from existing widget:

$get_featured_pages = new WP_Query( array(
        'posts_per_page'            => -1,
        'post_type'                 =>  array( 'page' ),
        'post__in'                  => $page_array,
        'orderby'                   => 'post__in'
    ) );
    echo $before_widget; ?>
        <div class="services-block clearfix">
            <?php
            $j = 1;
            while( $get_featured_pages->have_posts() ):$get_featured_pages->the_post();
                $page_title = get_the_title();
                if( $j == 3 ) {
                    $service_class = "tg-one-third tg-one-third-last";
                }
                else {
                    $service_class = "tg-one-third";
                }
                ?>
                <div class="<?php echo $service_class; ?>">

Currently outputs all divs with class="tg-one-third" and one with tg-one-third-last. I need to target them individually to add icon styles. I've searched but struggled to find answers that used the above syntax.