How Many Wild Cores for 162 Orange Gemstones?

I don’t use the loot things often and have just been storing up orange gemstones from the cards event. Unfortunatel, I am 192 gemstones away from Crystal Rose Gwen. Assuming I can buy the 30 from the next phase of the cards, how many wild cores does it make sense to buy to get the other 162? How is the luck, usually?