player one - selling/sending the gold
player two - buying/receiving the gold
lets say you want to transfer 1 mil
Player one - buys uncut d stones, last i knew 48k each so player one buys 21. 21*48k is 1,008,000.
player two - buys fire/chaos runes. chaos is faster, but price is going up so you lose a lot more. fires is slower but you lose less, but takes more time. now you have to sell your fires/chaos until you have 31.5k tokkuls. each d stone will cost you 1.5k tokkuls (21*1.5k = 31.5k) you'll have to sell 31.5k fires since they sell for 1 tokkul each (cost of fires are 31.5k*9gp = 283.5k)
you'll have to sell 3.5k chaos at 9 tokkuls each ( 3.5k*130gp = 455k) chaos are still going up so it might cost you a lot more. 130 is roughly the cost of chaos runes as of today.
once player two has the 31.5k tokkuls, both players meet at the gem seller.
player one sells the d stones to the store, player two quickly buys them. remember to buy them quickly because the store "updates" and lets say there are 10 in there, it'll decrease to 9. so even though player one sold 10, player two will only be able to buy 9.
I think the limit to buy is 50 d stones per 4 hrs.
But doing chaos right now, you only gain 445k from that 1 mil. I recommend you do fire runes. chaos was what, 88-90gp and now they're 130gp
you could search forum for more detailed guides since they're so many of them though, but hope this helps or gives you the general idea of how it works and the costs.