Worth a read if you are new to the stock markets. Always compare market capitalisation because each company has a different amount of shares on issue.
From my personal notes, GSC has over 1.3 billion shares on issue. BGS has only around 240 million - big difference. At the same sp, GSC would be worth over 5 times BGS.
With resource companies, MC needs to be measured against something to compare value. As they are both at a similar stage of development, a comparison of each projects NPV would be worthwhile. I would apply a premium to GSC based on its A+ location however.
Like I said, the Pre Feasibility Studies from both companies will be very telling.
