According to both Albion and Twentythree, there is a bug with the achievement that allows you to be able to process sapphires. Apparently, it is unable to be completed.
We are looking into it, sorry for the delayed reaction.
I checked it, and yes, there's a wrong mission assigned to T4 sapphire unlock. You'd need to craft unrefined T3 gems, and thats just not possible
Will be fixed!