I am at a loss as to how much I can negotiate on the price of a diamond. Does the size of the loose stone play into the negotiation? I''m thinking of between 1 and 1.5 carat between D-G and ideal cut. Does brand play into the negotiation too? I want to purchase in person. Is it better to walk away and not buy after discussing the various price offers? Is there a time (am/pm), or best month or season etc to make a purchase?