Nanomachinery encapsulation

In products and production devices of gemstome metamaterial technology most of the inside machinery will likely be well encapsulated and protected from the outside.

• Protected against more or less aggressive gasses like oxygen and nitrogen respectively.
• Protected against dirt and dust.
• Protected against finger grease and whatnot.

For once there is actually a quite good (and not too misleading) analogy in biology.
Plants and fruits harbor a lot of chemical compounds within them

• that are critical for their proper function and
• that must not be exposed to the oxygen in the air.

This can be especially well seen in the case of fruits.
Cutting open apples or bananas and waiting a bit they quickly getting brown.

The same holds for advanced gemstone metamaterial technology and its manufacturing devices.
So from that perspective even the less ideal pure metals and metal alloys can be used inside.
If other weaknesses like the metals tendency to atomic diffusion at low temperatures at surfaces and dislocations is taken account for that is.