Jewellery to SGB/R-GDS

Hi,

I received gold jewellery as gift from my in-laws (approx.640 grams). I would like to convert my gold jewellery to either SGB or R-GDS. I would prefer SGB as it can be dematerialised & pledged. However, I am concerned about tax implications. Following are my primary concerns:

1. Does sale of gold jewellery to buy SGB attract Capital Gains Tax?
2. Does deposit of jewellery for R-GDS attract capital gains?
3. I don't have any bills as it was a gift during my marriage. Does converting to Bonds/Gold Deposit arise to any income tax issues in future? 
4. Are there any other legal/tax issues I should be concerned about?

Also, please advice if this is a bad idea from an investment point of view.

Thanks in advance,