These informations are valid if you were trading gold through a broker like forex brokers: 

1 Standard Lot means you put the bet exactly with the price level.

Example if Gold now is 800.00, it means with 1 S-Lot you put 800$ of your capital in the bet.
If Gold is now at 810.00, it means you put 810$ in the bet.

This is for the Bet Margin.


About total money requirement for opening 1 S-Lot:

The normal spread is 1$ or 100 pips down. It means you will need 100$ as preserve capital to outcome the broker spread.

So the calculation is:

For 1 S-Lot = you will need 100$ + Current Price exactly.

Example: Gold Ask is 810.00 now. That means you will need 100$ + 810$ = 910$ to LONG 1 S-Lot.

Of course you will need more than this number for risk management.

What about mini account?
Divide it into 10. It means 1 S-Lot is 10 times of 1 Mini Lot. That makes 1 M-Lot is 81$+10$=91$ for opening. Of course profit and loss is divided into 10 times smaller than Standard Lot.