As per query, subject services of in nature of 'repairs of jewellery' which are owned by end-customers of the jeweler.
Description of HSN 9988 (i.e. Manufacturing services on physical inputs owned by others) - Explanatory Notes to the Scheme of Classification of Services - is as under:
"The services included under Heading 9988 are performed on physical inputs owned by units other than the units providing the service. As such, they are characterized as outsourced portions of a manufacturing process or a complete outsourced manufacturing process. Since this Heading covers manufacturing services, the output is not owned by the unit providing this service. Therefore, the value of the services in this Heading is based on the service fee paid, not the value of the goods manufactured."
To my mind, GST @ 5 % at the hands of alleged job-worker is also incorrect. Correct tax-rate thereof is 18% as per Serial No. 25 (ii) of Notification No. 11/2017-Central Tax (Rate) (as amended till date).
This is becuase, in my view, the subject services are falling under HSN 9987 (i.e. Maintenance, repair and installation (except construction) services), more specifically under HSN 998722 (i.e. Repair services of watches, clocks and jewellery) & NOT under HSN 9988 (i.e. (i.e. Manufacturing services on physical inputs owned by others)) OR more particularly, under HSN 998892 (i.e. Jewellery manufacturing services).
These are ex facie views of mine and the same should not be construed as professional advice / suggestion. And I respect contrary views.