Modify the Comment Gravatar Size in Genesis

comment-gravatar.php

//* Modify the size of the Gravatar in comments
add_filter( 'genesis_comment_list_args', 'topleague_comments_gravatar' );
function topleague_comments_gravatar( $args ) {
	$args['avatar_size'] = 96; // change the number depending on your requirement 
	return $args;
}