when your crafting menue still show remnants for blanks, you should run the craft fixer. Now Blanks are using dust, and dust you get from salvage rog jewelry lv 50/51
to upgrade an existing rog with e.g. 1% cold craft a 17% cold gem (sc) put 1 dust/ash + the gem into the craftwindow and it will show you the cost of dust/ash to make it 2%
same goes for stats, but here you need a 28 stat gem of the stat you want to upgrade +1