How should you invest in gold and when can you sell it back to the issuer?

How should you invest in gold? 

 Sovereign gold bonds (SGBs) are not very liquid. You can sell them back to the issuer after five years. Gold ETFs have better liquidity. On physical gold, you have to pay 3 per cent GST. Buy according to need: SGB for long term, ETF if you need liquidity, and bars if you need to accumulate gold for daughter's marriage.