So, a guy on wordpress.stackexchange.com gave me this hint:
$args_jewellery = array(
'post_type' => 'jewellery',
'numberposts' => -1,
'meta_query' => array(
array(
'key' => 'select_brands',
'value' => '"' . $brand . '"',
'compare' => 'LIKE'
)
)
);
Now, why would it take me three days to wrap that shit in quotation marks and use LIKE?
Sigh!