Reclaimed gold generally comes from a few key places. Old and unwanted jewellery is a big one, the pieces people trade in, inherit, or simply no longer wear. Manufacturing scrap is another, the offcuts and filings left over when jewellery is made, since even the tiniest shavings are collected and reused. And a surprising amount comes from electronics, as gold is used in small quantities in things like circuit boards and connectors, which can be recovered and refined.
Once collected, all of this gold is sent to a refinery, melted down, purified, and brought back to the same standard as any newly mined gold, ready to become something new.