What exactly could this mean? Let's talk about it after the break.
The most obvious idea is that we will either be able to buy new gems directly from them, or else alchemists will be able to learn new types of transmutations. But with no new data on recipes or gems showing up in the patch data as of late aside from things already found on various vendors, we can't say for sure what this means. Will we learn how to turn Talasite into Living Rubies? Stars of Elune into Empyrean Sapphires? Will this be a whole new class of gems? My gut is that these may be recipes to convert blue gems into epic gems so that casual jewelcrafters can make the new trinkets, but if they're "gems thought lost to time," maybe it'll be all new stuff.
We'll have to see what happens when Mar'nah opens shop (or if someone finds new recipes or items related to gems or transmutation in the patch data somewhere), but in the meantime, what are your ideas for what this could mean?