You must have an account balance that meets the equivalent weight you wish to redeem.
Related articles:
How do I redeem Gold?:
http://help.stackermarket.com/en/articles/6099047-how-do-i-redeem-goldHow do I redeem Silver?:
https://help.stackermarket.com/en/articles/6098998-how-do-i-redeem-silverHow does the redemption process work?http://help.stackermarket.com/en/articles/5355753-how-does-the-redemption-process-work
Can I request specific products during redemption?http://help.stackermarket.com/en/articles/5355758-can-i-request-specific-products-during-redemption
What is the cost for shipping and insurance for redeemed bullion?http://help.stackermarket.com/en/articles/5355759-what-is-the-cost-for-shipping-and-insurance-for-redeemed-bullion