As per a business stand point, i was really not expecting a diamond sale at all this weekend. They've put the 3 most wanted items in game on sale. They were sure to sell diamonds at full price since people just wanted those. That is why when diamonds are at 50% or 100% i sit my arse on them till the said sale. It's called patience, people are so incline to sell their diamonds when they are on sale and get gold, but gold for what?? gear, stats etc. Come do your quests, dailies, minigames and enjoy the game. Get your own gear, sure if you wanna be endgame within a month, then spent 500$ to 1K of real money to be level 72/72 but you still won't have the TP for your skills you need and know how to play them.
Double diamonds will show up on small sales or expensive X or VIII runes. I made 200M a couple months ago by selling diamonds i bought at 100%, that i've kept for months, before selling them at 50K per. be patient with your diamonds and especially rubies. Rubies are even more rare than diamonds, the only way to get them by buying stuff with diamonds, not on sale. So rubies should be going for at least 80K. That is why i don't sell them anymore.
my 2 cents and point of vue
K/P/S/M/W 98/98/98/98/98
Disturbed guild leader on mithras 
BTW i do live under a bridge, i am Green, i can dish it out as good as i get
There are no better server than Reni, best place to be!!!!!