Look at the market at the auction house, then collect the gems at a low price (the gems in the auction house are still relatively expensive), and just cut them and sell them. You should keep enough liquidity on you, because not all gems can be sold at once, and it is really impossible to reduce the price. As long as you consider many factors, making money is not a problem, but one thing, don't be too greedy, lest there be a financial crisis, make a joke, or gems in different periods. You can study the rest slowly by yourself.