The rate quoted on the Mint masthead is Rs. 2043.50 per gram. Tanishq's base rate is 2120. They charge about 5% margin (it varies as per a sliding scale - it's 5% for a 10 gram coin) plus 1% sales tax. The actual rate for a 10 gram biscuit is 2247. They will buy back Tanishq biscuits at the base rate (2120) if you buy ornaments from them with the proceeds. In case it is a cash buyback they will deduct 5% and give you 2014. So the net buy/sell margin actually works out to about 11% including the tax.
Shubh Jewellers quoted 2088 as their base rate, plus 1% tax. Their buyback for Shubh biscuits is currently is at 51 rupees less, that works out to 2037.
As expected, the buyback is at a rate slightly less than the day's benchmark rate. The rate at which they sell to us differs widely.