@reddo everything is saved as a meta to the post or page you are editing. For posts and pages:
$open_graph_title = get_post_meta( $post->ID, 'open_graph_title', true );
$open_graph_description = get_post_meta( $post->ID, 'open_graph_description', true );
$open_graph_image = get_post_meta( $post->ID, 'open_graph_image', true );
$open_graph_type = get_post_meta( $post->ID, 'open_graph_type', true );
For defaults:
$default_title = get_option('_open_graph_title');
$default_description = get_option('_open_graph_description');
$default_type = get_option('_open_graph_type');
$default_image = get_option('_open_graph_image');
For home:
$open_graph_title = get_option('_home_open_graph_title');
$open_graph_description = get_option('_home_open_graph_description');
$open_graph_type = get_option('_home_open_graph_type');
$open_graph_image = get_option('_home_open_graph_image');