The best method is to simply pay for an authentication service.
But here's a way you can do it for FREE!
- Bring pre-owned watch which is of "concern" to the Authorised Watch Service Centre to have the bracelet resized to fit your wrist.
- Bracelet size adjustment service is FOC!
- To adjust the watch bracelet, the watch will be exposed to close inspection by a watchsmith.
- If the said watch was not genuine, alarm bells will be ringing! (OK, maybe not literally, but you get the point!)
Disclaimer : Perform the above at your own risk. If watch found to be non-genuine, it may be confiscated.
Conclusion : When buying pre-owned watch, send watch for resizing before making the payment.
List of various Authorised Watch Service Centre has been graciously compiled by MWF Member - JeepWH.
Refer here ---
http://www.malaysiawatchforum.com/index.php?topic=15860.0