These two achievements require crafting a Radiant Star gem of the four original types: topaz, ruby, emerald, and amethyst. Finding the recipes is no longer an issue because in the 2.0.1 patch, all gem recipes through Marquise were automatically trained (or gained on jeweler levels - mine started at 10 so I can't check). So, prior to the expansion, one could farm hundreds of Flawless Square gems at level 60 and slowly work their way up to a Radiant Star.
Unfortunately, once you hit level 61, Flawless Squares no longer drop. Only Marquise and Imperial gems do.
Given the very small window where Flawless Square gems are eligible to drop, the high number of gems required, and the low amount of experience required to get out of this range, is there any reasonable method for acquiring these two achievements in RoS?