all you need to do is to go to market place NPC - click the special deals - look for upgraded weapons or armors then buy - next step look for (NPC) Blacksmith Techton if you are in Heidel then click (Extraction) Click the (Extract Black stone) put the gear that you bought at marketpalce then click (Extract) - Tadaaaa! you have your black stones for upgrade .
Note: buying +8 weapons above will give you random number of black stone weapons.
buying +6 armors above will give you random number of black stone armors.
Tips when buying:
buy +7 weapos and +5 for armors so you can have the equal amount of blackstone with the said upgrade .
always check the price of black stone you want to extract in the (upgrade) section in Marketplace so you can make sure you did bought cheaper than what is auctioned in the marketplace .
you can also use this process if you want to have easy silvers just take note of the prices of the things you buy and how much you can earn out of it .
thanks happy gaming .