Query (built in) Categories and Advanced Custom Fields?

Give this one a try:

$args_jewellery = array(
    'post_type' => 'jewellery',
    'numberposts'   => -1,
    'meta_query' => array(
        array(
            'key' => 'select_brands',
            'value' => '"' . $brand . '"',
            'compare' => 'LIKE'
        )
    )
);

And here’s a link to the WP Query custom field parameters documentation page.