So you would have a gen drill until you find 3 diamonds or 192 coal to macerate into dust to make industrial diamonds... That is pretty pointless if you ask me, one of the first things i acquire after i have a generator, macerator and electro furnace is 3 diamonds to make myself a diamond drill. Why would i want to make one that i will never use after i have those 3 diamonds?
The RP2 gems are very useful for other things such as making cutters (to make sub blocks) and in the future those gems are going to be used for lots of other things. Hence why they, among tungsten etc, are part of RP2 world with so few uses. They will have a use in a future release of RP2 so don't throw them away.
If you have too many of them just make gem blocks which cuts the required storage in 9.